This should cover most cases, including hooks.
What this specifically does is change some less useful messages for more
contextualized ones, including tying specific configurations to actions
taking place. This is particularly visible in hooks, and hopefully
provides some amount of discoverability.

Also of note:
- ebin/ directory copying is called explicitly when done since people
  have issues with that
- paths for compiled files are made relative since the analysis list
  shows the full paths already
- hooks are a bit more verbose but also more useful.

This was due to a subtle mistake in the new code in
https://github.com/erlang/rebar3/pull/2322 which optimized the search
behaviour of files not found by EPP. The patch mistakenly always kept
the top-level src/ directory for an app even if it did a lookup in
recursive ones.

This patch tracks and maintains the proper subdirectory hierarchy. To
keep performance adequate, the lists:keyfind/3 function is used, which
is also now a NIF to the same extent as lists:member/2; manual lookups
would likely end up reducing performance, particularly in deep
hierarchies.

A test case has been added to track the regression.
Reported by @elbrujohalcon

This commit makes rebar_compiler_erl to start a gen_server that acts
as a filesystem cache, avoiding re-scanning it over and over.

- Can't deal with := in map type declarations
- maps:update_with didn't exist back then so we reinvent it for the few
  months until we deprecate OTP 18

This moves the old DAG stuff out from the main code paths and
substitutes it with the new epp-based DAG work.

Also fixes previous work for integration tests:

- consider ptrans from erl_opts in app ordering
- display proper app compilation info messages due to reordering

While leaving the old one in place, prep the ground for new analysis
phases for the DAG work. The new DAG functions are added, but not hooked
in yet.

Fixes to the EPP handling have also been added due to issues in
resolving include_lib information

This commit is a transition point that makes some assumptions about new
callbacks for the compiler modules, which will likely not hold when it
comes to making epp be able to read and handle multiple applications at
once (so it can resolve parse transforms and behaviours across OTP
apps).

As such, a follow-up commit is going to be completing that one and
changing its API in incompatible ways; if you find this commit during a
bisect, it's probably not a good one in which to run a bisection.