arrow

GH-44392: [GLib] Add GArrowDecimal32DataType (#44580)



### Rationale for this change

`arrow::Decimal32Type` data type has been introduced. It is also necessary to support the same data type in GLib.

### What changes are included in this PR?

This PR implements `GArrowDecimal32DataType`.

### Are these changes tested?

YES

### Are there any user-facing changes?

Before this change `garrow_decimal_data_type_new()` returns `GArrowDecimal64DataType` if the precision is less than `garrow_decimal64_data_type_max_precision()`.
After this change, it returns `GArrowDecimal32DataType` if the precision is less than garrow_decimal32_data_type_max_precision().

* GitHub Issue: #44392

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