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GH-37440: [C#][Docs] Add Flight SQL supported functions to status.rst (#37441)

### Rationale for this change

Update the feature support documentation to reflect that Flight SQL is now supported with C#

### What changes are included in this PR?

The feature support matrix for Flight SQL now lists functions supported with C#

### Are these changes tested?

N/A

### Are there any user-facing changes?

Yes, the documentation.

No

Closes issue #37440 
* Closes: #37440

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