GH-39248: [JS] Unify code paths for utf8 and largeUtf8

[domoritz]

Reduce the code size by using common code paths. We only call Number a few times on numbers, which should be a noop.

• Closes: [JS]: Unify code paths for utf8 and largeUtf8 #39248

[domoritz]

@ursabot please benchmark lang=JavaScript

[ursabot]

Benchmark runs are scheduled for commit 4da251b. Watch https://buildkite.com/apache-arrow and https://conbench.ursa.dev for updates. A comment will be posted here when the runs are complete.

[conbench-apache-arrow]

Thanks for your patience. Conbench analyzed the 1 benchmarking run that has been run so far on PR commit 4da251b.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details.

[domoritz]

Reviewed as part of #39258.

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 6 benchmarking runs that have been run so far on merge-commit 9c097d5.

There were 2 benchmark results indicating a performance regression:

• Commit Run on ursa-i9-9960x at 2023-12-18 04:06:30Z
  • tpch (R) with engine=arrow, format=native, language=R, memory_map=False, query_id=TPCH-20, scale_factor=1
  • tpch (R) with engine=arrow, format=parquet, language=R, memory_map=False, query_id=TPCH-20, scale_factor=1

The full Conbench report has more details. It also includes information about 4 possible false positives for unstable benchmarks that are known to sometimes produce them.