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GH-34950: [C++][Parquet] Support encryption for page index (#36574)

### Rationale for this change

Parquet modular encryption requires page index to be encrypted if the column chunk is encrypted. This feature is missing for now.

### What changes are included in this PR?

Support both encryption and decryption for parquet page index.

### Are these changes tested?

Added round trip tests in write_configurations_test.cc and read_configurations_test.cc.

### Are there any user-facing changes?

NO.
* Closes: #34950

Authored-by: Gang Wu <ustcwg@gmail.com>
Signed-off-by: Antoine Pitrou <antoine@python.org>