Use the ert plugin mechanism to install forward models

[verveerpj]

Resolves equinor/ert#9147

This will break Everest, to be fixed by: equinor/ert#9148

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 10.52632% with 17 lines in your changes missing coverage. Please review.

Project coverage is 87.39%. Comparing base (974266c) to head (acde21c).

Files with missing lines	Patch %	Lines
src/everest_models/forward_models.py	0.00%	16 Missing ⚠️
src/everest_models/everest_hooks.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #75      +/-   ##
==========================================
- Coverage   87.79%   87.39%   -0.40%     
==========================================
  Files         133      134       +1     
  Lines        3350     3356       +6     
==========================================
- Hits         2941     2933       -8     
- Misses        409      423      +14     

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[DanSava]

Looks good to me, but maybe @yngve-sk should also take a look given he is a bit more familiar with ForwardModelStepPlugins

[yngve-sk]

I think this is a step in the right direction, removing all the config files. This is quite generic and in the long term we should explicitly type out one forward model per script (especially if we have validations that can be put there). But with all validations still packed inside the executables I suppose it has the same behavior as the old-style format.

[verveerpj]

I think we should remove the everest plugin functionality in the long run. Since the get_forward_models hook was only used in testing, I removed it as a first step. Please let me know what you think.

[DanSava]

👍