Refactor keystore

What I Did

• Updated keystore to select key entries in one statement instead of two
• Updated decryption and observer to only load keystore entries if something needs to be decrypted or encrypted

Implications

This may affect updating of records in particular.

Testing

• Install this package in TPS or ArtMoney Laravel systems
• Ensure encryption and decryption works as expected
• Take special care to test updating of records, and ensuring the appropriate users / keys can decrypt again.