.list.index_of_in() architectural review PR

[itamarst]

This PR implements a sketch of .list.index_of_in() as described in #20626

The questions I would definitely like feedback on at the moment are:

1. Is using amortized_iter() the right approach?
2. Is using needles.iter() the right approach?

[itamarst]

It's also possible the casting logic in Polars will need to be extended; CastingRules::FirstArgLossless isn't what we want since it casts the needles e.g. to List[Int64], we'd need some new option like CastingRules::FirstArgInnerLossless or something that casts to the inner type of the first argument.

[codecov]

Codecov Report

Attention: Patch coverage is 93.24324% with 5 lines in your changes missing coverage. Please review.

Project coverage is 79.70%. Comparing base (958d00f) to head (9fc4d5f).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...s/polars-ops/src/chunked_array/list/index_of_in.rs	91.83%	4 Missing ⚠️
crates/polars-plan/src/dsl/function_expr/list.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20733      +/-   ##
==========================================
- Coverage   79.75%   79.70%   -0.05%     
==========================================
  Files        1561     1562       +1     
  Lines      221785   222004     +219     
  Branches     2530     2530              
==========================================
+ Hits       176885   176955      +70     
- Misses      44318    44467     +149     
  Partials      582      582              

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