Implement PEM string support to connect to discovery API and Schema Registry

Problem to solve

Currently we don't have support to pass the PEM as string format while making connection to DA and SR.

Goal

Right now, it’s seems we’re only supporting location base certs. We need to add ssl.certificate.pem & ssl.key.pem options for DA and SR.

What does success look like, and how can we measure that?

• Pass the certs as PEM String format and able to produce & consume AVRO messages.