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GH-41298: [Format][Docs] Add a canonical extension type specification for UUID (#41299)

### Rationale for this change

Several users have expressed a need for a UUID type. This is to provide a canonical UUID extension type specification.

### What changes are included in this PR?

This adds to documentation of canonical extension types.

### Are these changes tested?

No as only docs are changed.

### Are there any user-facing changes?

No.
* GitHub Issue: #41298

Lead-authored-by: Rok Mihevc <rok@mihevc.org>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Signed-off-by: Rok Mihevc <rok@mihevc.org>