Register plugin from entry points

[Ni-g-3l]

Hello

As suggest here I implemented the support of entrypoints in order to make the process of adding plugin to REZ easier.

Closes #1661

Feel free to add feedback !

Have a great day

[codecov]

Codecov Report

Attention: Patch coverage is 67.34694% with 16 lines in your changes missing coverage. Please review.

Project coverage is 59.38%. Comparing base (c039654) to head (a7fa195).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
src/rez/plugin_managers.py	67.34%	12 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1872      +/-   ##
==========================================
+ Coverage   59.27%   59.38%   +0.10%     
==========================================
  Files         126      126              
  Lines       17217    17246      +29     
  Branches     3017     3020       +3     
==========================================
+ Hits        10206    10241      +35     
+ Misses       6326     6320       -6     
  Partials      685      685              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[JeanChristopheMorinPerso]

Thanks @Ni-g-3l for creating this PR. I left a couple of comments that will need to be addressed before we can consider merging it.

Also, if you have the time and want to, we should adjust our newly written plugins doc (https://rez.readthedocs.io/en/stable/plugins.html).

[Ni-g-3l]

Hello ! I fixed a big part of your comments, but I still not understand how you want resolve the plugin install with pip in tests

[JeanChristopheMorinPerso]

Thanks @Ni-g-3l . I left a comment to clarify what I mean about the tests.

[Ni-g-3l]

If you prefer this format of build system, we should update plugins doc by replacing setup.py part by a pyproject.toml.

[JeanChristopheMorinPerso]

Ok, sorry for the noise @Ni-g-3l. There are a couple of things I wanted which were easier to do myself than do the back and forth in a PR.

I also removed and re-added the vendored dependen.cies (and added the missing ones) and made sure they are compatible with python 3.7+.

I think the last thing will be to review the docs you wrote. I'll try to do that soon.

Thanks!

[Ni-g-3l]

Don't worry ! Happy to help ! I take a look at your commits and understand it ! I will do it the same way next time :)

Yes ! I will update doc according to your commits