feat(crypto): add aes gcm algorithm

[inkedsquid]

What does this PR do ?

This PR deprecates the legacy aes-256-cbc cipher and introduces support for the more secure aes-256-gcm encryption algorithm.

To preserve backward compatibility, aes-256-cbc remains the default behavior. The new aes-256-gcm cipher is opt-in via a configuration setting. Migration documentation and a script snippet are also provided directly in the README.

How should this be manually tested?

• Step 1: Have a .enc.json file generated with the aes-256-cbc cipher
• Step 2: Initialize a Vault instance
• Step 3: Use the migration script snippet provided in the README.md to re-encrypt the secrets
• Step 4: Inspect the newly generated .enc.json file. The encrypted strings should now contain 3 segments separated by dots: <encrypted-data>.<iv>.<auth-tag>.

Other changes

• Replaced mock-fs with native temporary files (fs.writeFileSync) in test/Vault.test.ts, as mock-fs breaks the test suite on modern versions of Node.

[kuzzlebot]

🎉 This PR is included in version 2.1.0-beta.2 🎉

The release is available on:

• GitHub release
• npm package (@beta dist-tag)

Your semantic-release bot 📦🚀

[kuzzlebot]

🎉 This PR is included in version 2.2.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot 📦🚀