Split up the compiler DAG

Add vendor_hex_core.sh

We're planning to move the vendor.sh script from hex_core to hex,
but if you'd prefer it stays there it's not a problem. Thought by
moving it here I think it's a bit easier to use anyway.

This is another tricky commit towards replacing the current module
analysis with EPP. The compiler DAG is now being shared across multiple
applications being compiled, rather than a per-application basis, which
promises to allow better ordering, parallelism, and more thorough
invalidation of runtime dependencies when they are modified.

This however required changes:
- The compiler DAG is no longer private to `rebar_compiler`, and has
  been extracted to the `rebar_compiler_dag` module
- The compiler DAG is now started by the `rebar_prv_compile` module,
  which oversees the calls to `rebar_compiler` for each OTP application
- The compiler DAG has been refactored to use a "dirty flag" to know if
  it was modified, rather than just tracking modifications in a
  functional manner, since the scope change (going multi-app) makes it
  impossible to cleanly use the functional approach without much larger
  changes
- The DAG used to be cached within each OTP application. This is no
  longer possible since it is shared. Instead the DAG is stored in the
  state's deps_dir, which allows to cleanly split caches between regular
  apps for the user's project and plugins
- The DAG supported a "label" mode that was used to store distinct DAGs
  for extra_src_dir runs and regular modules; this label is now used
  (and extended to `rebar_prv_compile` internals) to distinguish between
  "compile runs", such as "project_apps", or just "apps" (deps). The
  label is optional (i.e. not used by plugins which have no such need)
- The extra_src_dirs for each app is now compiled using the main app's
  DAG, but the run takes place later in the compilation process. This
  may need changing to detect and prevent dependencies from src_dirs
  into extra_src_dirs, but this should not technically be a problem for
  runtime anyway.
- Reworked the support for extra_src_dirs that are at the root of an
  umbrella project (and therefore do not belong to any single app) to
  use the new structure, also as part of the project_apps DAG.

All tests keep passing, and this puts us in a better place to use EPP
with cross-app support in the near-future.

Revert "Introduce rebar_uri to avoid deprecation warnings on OTP 23 [master]"

Introduce rebar_uri to avoid deprecation warnings on OTP 23 [master]

(cherry picked from commit 08eb611a3d)

(cherry picked from commit fa577bc46e)

(cherry picked from commit 1c9e91b80a)

Attempts to bridge http_uri (deprecated in OTP 23)
and uri_string (available as of OTP 21+).

(cherry picked from commit 7057cbe281)

Proper Unicode handling in port process output

Update compiler hooks order and internal compiler phases

The problem is that the shell util handlers receive a byte stream, which
we handle as a list coming from a port. However the byte stream is utf-8
encoded in most systems, which breaks encoding expectations (binaries
only) for Erlang.

This patch turns the list of characters to a binary for all shell calls,
before re-encoding it properly as unicode lists to keep the format compatible.

Fixes #2205

get a sorted list of modules for coverage output (screen and HTML)

Run dialyzer for extra_src_dirs

This is a new way to orient the code and would allow better
parallelization or multi-app scan phases

This allows breaking apart the pre-hooks from the rest of the
compilation steps, as a preliminary step towards being able to do some
analysis on all project apps at once before actually compiling them.

remove warning when booting applications in the shell

This warning is emitted every single time one starts a shell with applications
configured for automatic startup (e.g. `{shell, [{apps, [cowboy]}]}`).

Infortunately it does not make any sense: people who use this feature need it
to interact with their application or library during development, and are
therefore subjected to the warning every single time they start the shell even
though this is the right way to use it.

While the shell is not to be used to run applications in productions, those
who do it won't be stopped by a warning.

Ultimately, the warning annoys people who use the feature as intended, and do
nothing to stop people who abuse it. Thus I believe it should be removed.

See https://github.com/erlang/rebar3/issues/2206.

close #2206

Allow passing arguments in r3:do and r3:async_do

async_do with arguments is useful for debugging a particular suite/test
with r3:break()

Example session:
Add r3:break() in recompile_when_hrl_changes test in test/rebar_compile_SUITE.erl

rebar3 shell
...
1> r3:async_do(default, ct, "--suite=test/rebar_compile_SUITE.erl --case=recompile_when_hrl_changes").
ok
Running Common Test suites...
%%% rebar_compile_SUITE:
=== BREAK ===

2> r3:resume().
ok
3> .
All 1 tests passed.

Allow users to override default hex auth config

OTP 23 [master] compatibility

add rebar_string:trim function for removing all leading/trailing whitespace

For OTP 19 and earlier compatibility.

This function was used for trimming the version from a `{file, File}` app
vsn in .app.src but caused a crash because it did not exist.

Switching to uri_string as the warning suggest
would ruin OTP 20 compatibility.

See [1] for context.

1. https://bugs.erlang.org/browse/ERL-1113

Switching to uri_string as the warning suggest
would ruin OTP 20 compatibility.

Add `--statistics` option to dialyzer command

In some cases its nice to have dialyzer statistics out of box without
any additional steps.

Fix epmd start on windows

Windows does not have the same quoting rules as Unix so
we need to use platform independent quoting. Also for
os:cmd like operations we do not expect the program to
read any input so in order for it to work on windows we
should put -noinput there.

In r3_hex_core.erl we set default hex config. For example, we set the
api_organization to be undefined. By merging the hex auth config into
the default config this way round we allow users to override the default
config.

Allow cleaning specific apps or deps only

Disable bbmustache escaping

This will allow project with larger dependencies sets to clean only the
apps they want to when testing or changing small things, rather than
forcing a rebuild of the whole dep set.

Also allows cleaning up apps, not just deps.

We never really need that and nobody would expect it either. We're
rendering normal files, not HTML.

Handle missing OTP apps better