refactor(rust): Move sum kernel to polars-compute

[orlp]

This was the last bit of machinery that relied on the old Simd trait ecosystem in polars-arrow, so I could remove that. We also lost a dependency on multiversion. We might have to re-evaluate dynamic dispatch to AVX512 (which was the only thing multiversion was doing as we're compiling with AVX2 by default) for the sum kernels at a later point.

[ritchie46]

We might have to re-evaluate dynamic dispatch to AVX512 (which was the only thing multiversion was doing as we're compiling with AVX2 by default) for the sum kernels at a later point.

I think it's fine. For Polars cloud we can compile for avx512 directly.

[codecov]

Codecov Report

Attention: Patch coverage is 79.48718% with 16 lines in your changes missing coverage. Please review.

Project coverage is 79.63%. Comparing base (79eedcf) to head (221fd6e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-compute/src/sum.rs	80.00%	14 Missing ⚠️
...pe/src/executors/sinks/group_by/aggregates/mean.rs	66.66%	1 Missing ⚠️
...ipe/src/executors/sinks/group_by/aggregates/sum.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20867      +/-   ##
==========================================
- Coverage   79.64%   79.63%   -0.01%     
==========================================
  Files        1571     1567       -4     
  Lines      223186   223037     -149     
  Branches     2554     2554              
==========================================
- Hits       177751   177615     -136     
+ Misses      44850    44837      -13     
  Partials      585      585              

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