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GH-39232: [C++] Support binary to fixed_size_binary cast (#39236)



### Rationale for this change
Add binary to fixed_size_binary cast.

### What changes are included in this PR?
Add binary to fixed_size_binary cast.

### Are these changes tested?
Yes

### Are there any user-facing changes?
No

* Closes: #39232

Authored-by: Jin Shang <shangjin1997@gmail.com>
Signed-off-by: Antoine Pitrou <antoine@python.org>