Add support for RSA public key content in cachingRsaPublicKey and rsaPublicKey options

Enhanced cachingRsaPublicKey and rsaPublicKey configuration options to accept PEM-encoded RSA public key content directly, not just file paths.

Configuration options will accept either:

• File path (existing behavior): /path/to/public.key
• PEM content (new): ----BEGIN PUBLIC KEY----\nMIIB...

This will matches JDBC connector behavior