[FEAT] add list.value_counts()

[andrewgazelka]

This PR implements the list.value_counts() function and refactors Map types to use a more explicit key-value structure. It also includes various improvements and bug fixes across the codebase.

Key changes

1. Implemented list.value_counts() function

2. Refactored Map type representation

   • Updated DataType enum in src/daft-schema/src/dtype.rs to use explicit key and value types

3. Improved error handling and type checking

   • Enhanced type checking in various parts of the codebase
   • Improved error messages for better debugging

4. Performance optimizations

   • Refactored some operations to be more efficient, especially in list and map operations

5. Code cleanup and minor improvements

   • Removed unnecessary clones and improved code readability
   • Updated comments and documentation

[codspeed-hq]

CodSpeed Performance Report

Merging #2902 will not alter performance

_{Comparing andrew/list-value_counts (35d65d3) with main (f5cf5af)}

Summary

✅ 17 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 77.24771% with 124 lines in your changes missing coverage. Please review.

Project coverage is 78.36%. Comparing base (46c5a7e) to head (35d65d3).
Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
src/common/tracing/src/lib.rs	15.38%	22 Missing ⚠️
src/daft-core/src/array/fixed_size_list_array.rs	0.00%	20 Missing ⚠️
src/daft-core/src/array/mod.rs	39.28%	17 Missing ⚠️
src/daft-functions/src/list/value_counts.rs	61.90%	16 Missing ⚠️
src/daft-table/src/lib.rs	44.44%	10 Missing ⚠️
src/daft-dsl/src/functions/map/get.rs	52.94%	8 Missing ⚠️
src/daft-core/src/array/ops/from_arrow.rs	76.92%	6 Missing ⚠️
src/daft-core/src/series/ops/list.rs	57.14%	6 Missing ⚠️
src/daft-schema/src/schema.rs	54.54%	5 Missing ⚠️
src/daft-core/src/array/ops/list.rs	96.00%	4 Missing ⚠️
... and 5 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2902      +/-   ##
==========================================
+ Coverage   76.34%   78.36%   +2.01%     
==========================================
  Files         597      603       +6     
  Lines       71388    71464      +76     
==========================================
+ Hits        54504    56002    +1498     
+ Misses      16884    15462    -1422     

Flag	Coverage Δ
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Files with missing lines	Coverage Δ
daft/expressions/expressions.py	93.75% <100.00%> (+0.37%)	⬆️
src/daft-core/src/array/list_array.rs	84.11% <100.00%> (+0.58%)	⬆️
src/daft-core/src/array/ops/arrow2/comparison.rs	98.70% <100.00%> (ø)
src/daft-core/src/array/ops/cast.rs	87.50% <100.00%> (+0.02%)	⬆️
src/daft-core/src/array/ops/groups.rs	98.18% <100.00%> (ø)
src/daft-core/src/array/ops/map.rs	87.50% <100.00%> (+14.77%)	⬆️
src/daft-core/src/array/ops/sparse_tensor.rs	100.00% <100.00%> (ø)
src/daft-core/src/array/serdes.rs	87.74% <100.00%> (+0.32%)	⬆️
src/daft-core/src/array/struct_array.rs	79.71% <ø> (ø)
src/daft-core/src/datatypes/logical.rs	74.07% <ø> (ø)
... and 28 more

... and 81 files with indirect coverage changes

[desmondcheongzx]

Flushing what I have right now, seems you wanted to iterate a bit more on it.

Could we also update the PR description so we get a proper commit message?

[desmondcheongzx]

Discussing offline---what happens with lists of nested values?

Also, could we add this new expression to docs/source/api_docs/expressions.rst?

[desmondcheongzx]

Looks good, thanks for all the changes!