perf: Preserve Column repr in ColumnTransform operations

[nameexhaustion]

This makes it so that recursive casts / renames applied by ColumnSelector avoid materializing scalar / partitioned columns.

Introduces 2 new functions on Column. For usage, you would get a Series from get_backing_series(), apply some elementwise transformations, then construct an output Column using to_new_from_backing(). This can in the future be used in more places that perform elementwise operations.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 16 lines in your changes missing coverage. Please review.

Project coverage is 81.30%. Comparing base (bbb0736) to head (d8d9244).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-core/src/frame/column/mod.rs	45.45%	12 Missing ⚠️
crates/polars-core/src/frame/column/partitioned.rs	0.00%	3 Missing ⚠️
...ces/multi_file_reader/extra_ops/column_selector.rs	95.65%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #23648      +/-   ##
==========================================
- Coverage   81.31%   81.30%   -0.02%     
==========================================
  Files        1641     1641              
  Lines      223142   223167      +25     
  Branches     2837     2837              
==========================================
- Hits       181449   181445       -4     
- Misses      40994    41023      +29     
  Partials      699      699              

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