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GH-36570: [Dev] Add "Component: Swift" label to PRs (#36571)

### Rationale for this change

We already have the "Component: Swift" label but it's not added to Swift related PRs automatically.

### What changes are included in this PR?

Add a configuration for labeler.

### Are these changes tested?

No. I want to test this on main.

### Are there any user-facing changes?

No.
* Closes: #36570

Authored-by: Sutou Kouhei <kou@clear-code.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>