refactor(rust): Replace DynArgs with an enum containing all its variants

[3ok]

This PR presents one way to fix #18595.

Information present in DynArgs was being lost after a serialization/deserialization roundtrip, so I had to implement Serialize and Deserialize in order to handle them.

This is my first contribution so I'm pretty excited about that!

[codecov]

Codecov Report

Attention: Patch coverage is 91.39785% with 8 lines in your changes missing coverage. Please review.

Project coverage is 79.86%. Comparing base (962b576) to head (4ada469).
Report is 35 commits behind head on main.

Files with missing lines	Patch %	Lines
...ow/src/legacy/kernels/rolling/no_nulls/quantile.rs	78.57%	3 Missing ⚠️
...arrow/src/legacy/kernels/rolling/nulls/quantile.rs	83.33%	2 Missing ⚠️
...ow/src/legacy/kernels/rolling/no_nulls/variance.rs	87.50%	1 Missing ⚠️
...arrow/src/legacy/kernels/rolling/nulls/variance.rs	83.33%	1 Missing ⚠️
...polars-core/src/frame/group_by/aggregations/mod.rs	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18746      +/-   ##
==========================================
- Coverage   79.86%   79.86%   -0.01%     
==========================================
  Files        1517     1517              
  Lines      205542   205533       -9     
  Branches     2892     2892              
==========================================
- Hits       164156   164146      -10     
- Misses      40838    40839       +1     
  Partials      548      548              

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[ritchie46]

Hey @3ok. Thanks for the PR. Your conclusion is right. We need to support serde.

I only think we should do that on a different manner. I think we should get rid of DynArgs altogether and create a enum that supports serde, with variants for all DynArgs possibilities.

[3ok]

Hi @ritchie46, thanks for the feedback.

I only think we should do that on a different manner. I think we should get rid of DynArgs altogether and create a enum that supports serde, with variants for all DynArgs possibilities.

I have added a new enum RollingFnParams containing all DynArgs possibilities and changed all DynArgs occurrences with Option<RollingFnParams>.

[ritchie46]

Thanks!