GH-3826: Preserve component paths for Bloom filters

[costas-db]

Rationale for this change

Parquet column paths are component-based, but Bloom filters were stored under dot-string keys. A top-level field named a.b (["a.b"]) therefore collided with nested field a.b (["a", "b"]), allowing one column’s Bloom filter to overwrite the other.

What changes are included in this PR?

• Keys internal Bloom-filter maps by ColumnPath rather than flattened strings.
• Preserves the existing addBloomFilter(String, …) API and adds addBloomFilterForPath(ColumnPath, …) for structured callers.
• Keeps component paths intact when copying Bloom filters through ParquetRewriter.
• Adds a direct regression plus a readable expected-output JSON fixture.

Are these changes tested?

Before the fix, the focused reproduction reports:

"topLevelContainsOwnBloomValues" : false
"nestedContainsOwnBloomValues" : true

After the fix, both the direct and expected-output tests pass.

Also verified:

• Full TestParquetWriter
• TestParquetFileWriter
• ParquetRewriterTest
• spotless:check
• apache-rat:check

Are there any user-facing changes?

No on-disk format change. The existing string-based API remains compatible; this adds a component-based API for callers that already have a ColumnPath.

Closes #3826.