feat(parquet): compact level representation with generic writer dispatch (#9831)

# Which issue does this PR close?

<!--
We generally require a GitHub issue to be filed for all bug fixes and
enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax.
-->

- Spawn off from #9653 
- Contributes to #9731

# Rationale for this change

<!--
Why are you proposing this change? If this is already explained clearly
in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand
your changes and offer better suggestions for fixes.
-->

See #9731

# What changes are included in this PR?

Represent definition and repetition levels as `LevelData`/`LevelDataRef`
with `Absent`, `Materialized`, and `Uniform` variants, and thread this
through Arrow level generation, CDC chunking, and the generic column
writer.

Uniform level runs, such as required fields and all-null pages, can now
be encoded without materializing dense `Vec<i16>` buffers. Add bulk run
support to `LevelEncoder`/`RleEncoder` so repeated levels are encoded in
amortized O(1) after the RLE warmup, while preserving histogram, row
count, null count, page splitting, and CDC chunk accounting.

# Are these changes tested?

<!--
We typically require tests for all PRs in order to:
1. Prevent the code from being accidentally broken by subsequent changes
2. Serve as another way to document the expected behavior of the code

If tests are not included in your PR, please explain why (for example,
are they covered by existing tests)?
-->

All tests passing. Coverage exercises bulk RLE level encoding,
compact/uniform `LevelData` slicing and writer roundtrips across Parquet
v1/v2, and CDC/Arrow writer behavior including all-null and nested-level
cases.

# Are there any user-facing changes?

<!--
If there are user-facing changes then we may require documentation to be
updated before approving the PR.

If there are any breaking changes to public APIs, please call them out.
-->

None.

---------

Signed-off-by: Hippolyte Barraud <hippolyte.barraud@datadoghq.com>
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

Author: HippoBaro