[DEVEX-223] Add support for changing the root certificate

[w1am]

This pull request introduces support for specifying a custom TLS CA file in the eventstore crate. It includes changes to the ClientSettings struct, updates to the connection parsing logic, and new tests to validate the functionality.

Key changes:

TLS CA File Support:

• eventstore/src/grpc.rs: Added tls_ca_file field to ClientSettings struct and updated related methods to handle this new field. This includes adding a getter method and updating the parse_from_url function to parse the tlsCaFile parameter from the connection string.
• eventstore/src/grpc.rs: Modified NodeConnection::new to load the custom TLS CA file if provided, otherwise, it falls back to loading the platform certificates.