Support cert based authentication for config server

Is your feature request related to a problem? Please describe.
config server can be set up by request client cert:

• server.ssl.enabled=true
• server.ssl.client-auth=need

Ideally the spring cloud config client library should support the cert based authentication by some configuration.

Describe the solution you'd like
Currently the cert based authentication is supported in Azure Spring Cloud client lib via following properties:

• spring.cloud.config.tls.enabled
• spring.cloud.config.tls.key-store
• spring.cloud.config.tls.key-store-password
• spring.cloud.config.tls.key-password

Wondering if this implementation can be ported into spring cloud config client.

The source code of Azure Spring Cloud client lib can be found at: https://repo1.maven.org/maven2/com/microsoft/azure/spring-cloud-starter-azure-spring-cloud-client/2.2.0/spring-cloud-starter-azure-spring-cloud-client-2.2.0-sources.jar

Describe alternatives you've considered
N/A

Additional context
N/A

No repository files or tests are named. Start by reviewing the spring-cloud-config client entry points and the Azure Spring Cloud client source archive, focusing on the listed TLS properties; done should mean certificate-based client authentication can be configured for the config server connection.