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GH-44271: [C#] Add support for Decimal32 and Decimal64 (#44272)

### What changes are included in this PR?

Implementation of decimal32 and decimal64 for C#.
Tests for the implementation, including enablement of Archery tests.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

New types Decimal32Array and Decimal64Array.

Closes #44271
* GitHub Issue: #44271

Authored-by: Curt Hagenlocher <curt@hagenlocher.org>
Signed-off-by: Curt Hagenlocher <curt@hagenlocher.org>