HDDS-11070. Separate KeyCodec from reading and storing keys to disk

[Galsza]

KeyCodec is now only responsible for encoding and decoding keys, the rest of the functionality is in KeyStorage

For crypto-compliance we would like the non-compliant parts of the code to be as separated and as small as possible so that they will be easy to move to a new method. Here I'm separating these responsibilities so the KeyCodec is only encoding/decoding keys. Later it can be moved to a new module.

HDDS-11070

Tests should already cover this functionality, here is a green CI run: (It contained other changes regarding CertificateCodec) https://github.com/Galsza/ozone/actions/runs/9678884891