Add SSL, SASL and security properties as editable configurations to Cluster Link resource

[emrantalukder]

Currently the Confluent terraform provider does not allow the provisioning of a cluster link with a custom truststore certificate. ssl.truststore.(certificates|type) is not an editable configuration property.

Config Properties Example

sasl.jaas.config=org.apache.kafka.common.security.plain.PlainLoginModule required username='kafka' password='kafka-secret';
security.protocol=SASL_SSL
sasl.mechanism=PLAIN
ssl.truststore.type=PEM
ssl.truststore.certificates=-----BEGIN CERTIFICATE----- ... -----END CERTIFICATE-----

Other supported protocols and mechanisms such as mTLS and OAuth would benefit from the enhancement of adding all ssl and security related properties:

security.protocol=SSL
ssl.truststore.type=PEM
ssl.keystore.type=PEM
ssl.keystore.certificate.chain
ssl.keystore.key
ssl.key.password
ssl.truststore.certificates

# needed for oauth
sasl.oauthbearer.token.endpoint.url
sasl.login.callback.handler.class=

This is needed when provisioning hybrid cloud/on-prem architectures and migrations.

References:
Manage Security for Cluster Linking on Confluent Cloud
resource_cluster_link.go#L83