Credential Store CSKeyFile configuration item should not be mandatory

Current Situation

in the YADE configuration view the value for the configuration item CSKeyFile is mandatory when
a CredentialStoreFragment/CSAuthentication/KeyFileAuthentication is configured.

Desired Behavior

• It should be possible to create a CredentialStoreFragment/CSAuthentication/KeyFileAuthentication only with setting the value for the CSFile.
• If the CSKeyFile is not set than there is default location that is the same as the location for the CSFile file but with the extension .key
  • e.g. if the CSFile is config/live/credential_store.kdbx - config/live/credential_store.key key file will be expected