Refactor Resolver serialization + ball ball friction sub models

[ekiefl]

Instead of serializing a dumbed down version of Resolver via ResolverConfig, Resolver is itself serialized (as ~/.config/pooltool/physics/resolver.yaml).

Summary of changes:

• get_X_model functions are removed. It was an obfuscating abstraction.
• All physics models are expected to be attrs classes, so they can be serialized.
• Model attributes can be any type, so long as they are round-trip serializable. That means sub-models can exist as attributes of models.
• Each model has a model attribute. This is used as a cattrs structuring directive.
• Ball ball friction models were condensed to a single file.
• I still need to update docs/resources/custom_physics.md.

The default resolver.yaml now looks like this:

ball_ball:
  friction:
    a: 0.009951
    b: 0.108
    c: 1.088
    model: alciatore
  num_iterations: 1000
  model: frictional_mathavan
ball_linear_cushion:
  model: han_2005
ball_circular_cushion:
  model: han_2005
ball_pocket:
  model: canonical
stick_ball:
  english_throttle: 1.0
  squirt_throttle: 1.0
  model: instantaneous_point
transition:
  model: canonical
version: 6

[codecov]

Codecov Report

Attention: Patch coverage is 73.97260% with 57 lines in your changes missing coverage. Please review.

Project coverage is 44.74%. Comparing base (0e89b7f) to head (1e23f82).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
pooltool/physics/resolve/__init__.py	11.42%	31 Missing ⚠️
pooltool/physics/resolve/resolver.py	53.48%	20 Missing ⚠️
pooltool/serialize/convert.py	50.00%	4 Missing ⚠️
pooltool/physics/resolve/ball_ball/friction.py	93.54%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #171      +/-   ##
==========================================
+ Coverage   44.22%   44.74%   +0.52%     
==========================================
  Files         127      129       +2     
  Lines        8554     8684     +130     
==========================================
+ Hits         3783     3886     +103     
- Misses       4771     4798      +27     

Flag	Coverage Δ
service	44.74% <73.97%> (+0.52%)	⬆️

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[derek-mcblane]

Looks good!

And I think the inclusion of the Alciatore friction model will give better results for Mathavan.

[ekiefl]

Got around to adding new instructions for adding custom physics. Merging this now. Hopefully all goes well!