arrow

GH-15287: [Ruby] Merge column and add suffix in Table#join (#33654)

# Rationale for this change

Current implementation is always preserve column of join key. It is convenient if columns are merged.

# What changes are included in this PR?

- Columns from left and right are marged if;
  - Join key is a String or a Symbol (<= incompatible Change)
  - Join key is nil (natural join) (<= change in unreleased feature)
- New options `left_suffix=""` and `right_suffix=""` are introduced.
  - If it is empty (by default), join key(s) do not change.
  - If it is not empty, the suffix is appended to join key(s).

# Are these changes tested?

Yes.

# Are there any user-facing changes?

There are incompatible change when join key is a String or a Symbol.

* Closes: #15287

Lead-authored-by: Hirokazu SUZUKI <heronshoes877@gmail.com>
Co-authored-by: Sutou Kouhei <kou@clear-code.com>
Co-authored-by: Sutou Kouhei <kou@cozmixng.org>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>