feat: Improved array arithmetic support

[nameexhaustion]

• Adds support for performing arithmetic between numeric and array columns. The numeric value is broadcasted horizontally to every array element within each row, similar to list arithmetic.
• Broadcasting for arithmetic between 2 array columns is now done without materializing the input columns (although we still materialize for the input validity)
• Adds support flooring division for array columns
• Fixes an issue with incorrect outer validities when adding arrays (Incorrect outer validity for array arithmetic result #19838)

shape: (6, 8)
┌────────────────────┬──────┬────────────────────┬────────────────────┬────────────────────┬────────────────────┬──────┬────────────────────┐
│ a                  ┆ p    ┆ a * p              ┆ a * first(p)       ┆ first(a) * p       ┆ a // p             ┆ q    ┆ a + q              │
│ ---                ┆ ---  ┆ ---                ┆ ---                ┆ ---                ┆ ---                ┆ ---  ┆ ---                │
│ array[i64, (1, 2)] ┆ i64  ┆ array[i64, (1, 2)] ┆ array[i64, (1, 2)] ┆ array[i64, (1, 2)] ┆ array[i64, (1, 2)] ┆ i64  ┆ array[i64, (1, 2)] │
╞════════════════════╪══════╪════════════════════╪════════════════════╪════════════════════╪════════════════════╪══════╪════════════════════╡
│ [[1, 1]]           ┆ 1    ┆ [[1, 1]]           ┆ [[1, 1]]           ┆ [[1, 1]]           ┆ [[1, 1]]           ┆ null ┆ [[null, null]]     │
│ [[2, 2]]           ┆ null ┆ [[null, null]]     ┆ [[2, 2]]           ┆ [[null, null]]     ┆ [[null, null]]     ┆ null ┆ [[null, null]]     │
│ [[3, 3]]           ┆ 3    ┆ [[9, 9]]           ┆ [[3, 3]]           ┆ [[3, 3]]           ┆ [[1, 1]]           ┆ null ┆ [[null, null]]     │
│ [[null, null]]     ┆ 4    ┆ [[null, null]]     ┆ [[null, null]]     ┆ [[4, 4]]           ┆ [[null, null]]     ┆ null ┆ [[null, null]]     │
│ [null]             ┆ 5    ┆ [null]             ┆ [null]             ┆ [[5, 5]]           ┆ [null]             ┆ null ┆ [null]             │
│ null               ┆ 6    ┆ null               ┆ null               ┆ [[6, 6]]           ┆ null               ┆ null ┆ null               │
└────────────────────┴──────┴────────────────────┴────────────────────┴────────────────────┴────────────────────┴──────┴────────────────────┘

Table code

df = (
    pl.select(
        pl.lit(
            pl.Series(
                [[[1, 1]], [[2, 2]], [[3, 3]], [[None, None]], [None], None],
                dtype=pl.Array(pl.Array(pl.Int64, 2), 1),
            )
        ).alias("a"),
    )
    .with_columns(
        pl.int_range(1, 1 + pl.len())
        .pipe(lambda e: pl.when(e != 2).then(e))
        .alias("p"),
    )
    .with_columns(
        (pl.col("a") * pl.col("p")).alias("a * p"),
        (pl.col("a") * pl.first("p")).alias("a * first(p)"),
        (pl.first("a") * pl.col("p")).alias("first(a) * p"),
        (pl.col("a") // pl.col("p")).alias("a // p"),
    )
    .with_columns(
        pl.lit(None, dtype=pl.Int64).alias("q"),
    )
    .with_columns(
        (pl.col("a") + pl.col("q")).alias("a + q"),
    )
)

print(df)

Fixes #19356
Fixes #19838

[nameexhaustion]

Note: This file has mostly the same structure as the one for list arithmetic, but with some array specific adjustments.

[nameexhaustion]

Arrays have a simpler layout compared to lists, so we can also implement array<->primitive with the array side being broadcasted without materializing.

[nameexhaustion]

Factored out this and some other parts of list arithmetic for re-use

[nameexhaustion]

drive-by - changed the order of this enum matching to the same order of the comment (expand the diff above to see the comment)

[nameexhaustion]

moved to arithmetic/test_array.py below

[nameexhaustion]

Same parametrized test copied from list arithmetic. It has also extra parametrization to test operations between nested array types (array_side="both3").

[codecov]

Codecov Report

Attention: Patch coverage is 93.07590% with 52 lines in your changes missing coverage. Please review.

Project coverage is 79.37%. Comparing base (6ccb187) to head (6814121).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...lars-core/src/series/arithmetic/fixed_size_list.rs	92.49%	41 Missing ⚠️
...polars-core/src/series/arithmetic/list_borrowed.rs	92.00%	6 Missing ⚠️
...es/polars-core/src/series/arithmetic/list_utils.rs	95.29%	4 Missing ⚠️
crates/polars-plan/src/plans/aexpr/schema.rs	96.15%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19837      +/-   ##
==========================================
+ Coverage   79.33%   79.37%   +0.04%     
==========================================
  Files        1548     1550       +2     
  Lines      214245   214751     +506     
  Branches     2460     2460              
==========================================
+ Hits       169968   170464     +496     
- Misses      43719    43728       +9     
- Partials      558      559       +1     

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