Update hex_core and add mirror_of repo config

- removed deprecated maintainers field from config template in
  rebar_prv_packages

Add --generator option for eunit

Add a --fail_fast switch to common test

bump erlware_commons to 1.3.1

re-expose download/3 for backwards compatibility in git deps related plugins

This switch aborts the rebar3 run after the first test failure is
reported.

Since Common Test does not support this feature and it can be useful for
interactive development (a demand from one of the teams I work with), I
decided to add the feature as an experimental CT hook.

The hook notices any test failure, and forcefully aborts the current
script execution, but only during the initialization phase of the next
test; this ensure that all other hooks for a post-test failure have the
time to do things right.

The CT logs _will_ be interupted, and hooks of all kinds may also
suffer.

Since this might be a bit tricky to support internally, I will be fine
with a review that results in "no, Fred. Please test this in a project
plugin first" or if I get told to use profiles to mature the feature
(i.e. `rebar3 as failfast ct ...`) with a custom hook declaration.

For issue https://github.com/erlang/rebar3/issues/1974
Revert "add rebar.lock to template gitignore"

This reverts commit 8fb8a91130.

This reverts commit 8fb8a91130.

For issue https://github.com/erlang/rebar3/issues/1974

- fixes systests on darwin where previously the recursive cp would fail
   due to everything being copied after the last forward slash.
   Specifically, everything in  `systest/all_SUITE_data/` would be
   copied but not `all_suite_data` dir itself which the tests expected.

Fixing systest to use up to date plugin

prevents some failures when running

implement mib_first_files support in rebar_compiler_mib

mostly copy/paste from rebar_compiler_erl

consider A-MIB imports from B-MIB:

rebar compile MUST FAIL if mib_first_files is ["mibs/A-MIB.mib"]
rebar compile MUST SUCCEED if mib_first_files is ["mibs/B-MIB.mib"]

Support ignoring entire modules in xref results

Fix pkg name during update by using pkg_name understood by hex

- Added support to rebar_prv_xref for filtering out whole module. A
  module may now be added to the list of xref_ignores in rebar.config or
  via -ignore_xref() module attribute
  - Added unit test for whole module filtering support to xref CT suite

Fix load order for custom project builders and parse transforms

The app data, when set by `rebar3_app_discover` basically does not
include the modules if it was derived from the .app.src file, even if at
a later point the modules were compiled.

Since there is currently no clear way to add that information reliably
across all compiler versions in all types of compilers, we simply clear
the cache and re-derive the information when required.

This might have a small performance cost, but is required for
correctness whenever an application's first build is run. Specifically,
this bug was detected when a plugin included lager's parse transform,
and the application itself also required it, but two distinct versions
were needed.

This patch finalizes fixing this issue.

Compile time with parse transforms needs to have the deps first in scope
before the plugins

Due to building dependencies with potential artifacts such as parse
transforms or macros, project builder plugins should be included in the
path, but _after_ deps are loaded.

Doing otherwise means that if any of the dependencies is required at
compile time, those of a plugin might get used first.

search subdirectories as well for imports/transforms/behaviours

Fix path coverage loading artifacts

Add hint for `rebar3 new help` on `rebar3 help new`

The old path handling routine would force loading a bunch of
applications, but it did not necessarily unload them aside from specific
calls that the other test handlers used to need to do, but no longer
needed under the updated path management of 3.7.0.

The leftover calls in the cover compilation bits caused some apps to be
loaded and to remain loaded before tests started.