GH-48294: [Ruby] Add RecordBatch#merge

[Reranko05]

Rationale for this change

This adds Arrow::RecordBatch#merge with behavior analogous to
Arrow::Table#merge.

What changes are included in this PR?

• Add RecordBatch#merge
• Support merging with a Hash
• Support merging with another RecordBatch
• Support column addition, replacement, and removal (via Hash values of nil)
• Add tests covering the new behavior

Are these changes tested?

Yes. Added unit tests covering:

• add column
• remove column
• replace column
• merge with another RecordBatch
• invalid merge target

• GitHub Issue: [Ruby] Add Arrow::RecordBatch#merge #48294

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[github-actions]

⚠️ GitHub issue #48294 has been automatically assigned in GitHub to PR creator.

[github-actions]

⚠️ GitHub issue #48294 has been automatically assigned in GitHub to PR creator.

[kou]

+1

Could you unify common code in Table#merge and RecordBatch#merge to ColumnContainable#merge as a follow-up task?

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 4 benchmarking runs that have been run so far on merge-commit e6146ee.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 3 possible false positives for unstable benchmarks that are known to sometimes produce them.