DX-108149: Change function names to ENCRYPT/DECRYPT

[timhurskidremio]

For a better visual distinction between the new and the legacy encrypt functions, we'll rename the new functions to ENCRYPT and DECRYPT while keeping the legacy ones AES_ENCRYPT and AES_DECRYPT

AES_ENCRYPT and AES_DECRYPT will be deprecated in the future

This change also includes minor code tweaks for improved readability

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[timhurskidremio]

https://github.com/Vijeth-test/arrow-build/actions/runs/19804674552