GH-36472: [Ruby] Add run-end encoded array values and raw records - #51276

Rationale for this change

GH-36472 requests the same native Ruby conversion support for run-end encoded arrays as other arrays. Currently RunEndEncodedArray#values resolves to a GObject child property, while chunked values and record conversion raise NotImplemented.

What changes are included in this PR?

• Map logical positions to physical runs with Arrow's run-end utility, then convert the physical value through the existing native converters, including null and nested values.
• Add REE dispatch to array values, bulk/streaming record conversion, and the existing nested-array visitors.
• Remove the shadowing GObject values getter so Array#values is inherited. The physical child remains available through the existing values_raw method; logical_values is unchanged.

Are these changes tested?

Built the C++/GLib libraries from main at 68243c4ba and compiled the changed native Ruby extension on macOS arm64 with Ruby 4.0.6.

• New regression matrix: 43 tests, 339 assertions, covering all three run-end widths, a logical offset above 32 bits, sliced physical children, slices within runs, null runs, empty arrays/chunks, nested values and REE children, and both Table/RecordBatch bulk and streaming paths. Against the unchanged extension, these tests produce 6 failures and 34 NotImplemented errors.
• Full red-arrow suite: 2,710 tests, 3,014 assertions, zero failures/errors; two ORC omissions.
• GLib suite in the locally built core configuration: 2,238 tests, 2,299 assertions, zero failures/errors; 243 optional-component/platform omissions. A local preload excludes installed Arrow 25 optional typelibs from the Arrow 26 process. Both native GLib C examples pass.
• Repository-configured RuboCop 1.71.0, Ruby syntax, git diff --check, and the repository RAT license audit pass.

Are there any user-facing changes?

REE arrays now support native Ruby values and raw-record conversion.

This PR includes breaking changes to public APIs. RunEndEncodedArray#values returns a Ruby array of logical values instead of the GObject physical-child property. Callers needing that child should use the already available values_raw method.

AI assistance

OpenAI Codex was used to generate the implementation and regression tests and to run the validation described above.

• GitHub Issue: [Ruby] Add Arrow::RunEndEncodedArray#{raw_records,values} #36472