Simplify / Centralise Datasource Password Encryption

Where the datasource passwords differ the current approach to encrypt a datasource password requires a one to one mapping between the datasource and the security domain, for deployments with a large number of datasources this means an equal number of security domains also need to be defined.

This feature request is to review the options available to simplify this mapping between the datasource configuration and the domain to decrypt the password.

One suggestion is to store the encrypted for of the password with the datasource and use only a single security domain to decrypt all passwords.