Expose dynamic client cert resolver via C bridge for language SDKs

[brucearctor]

Context

Follow-up to #1338 / #1340.

The C bridge (temporalio-sdk-core-c-bridge) currently hardcodes client_cert_resolver: None in its TryFrom<&ClientTlsOptions> impl. This means language SDKs built on the C bridge (Python, Ruby, etc.) cannot use the dynamic certificate resolution feature.

Proposal

Add a client_cert_resolver_callback to the C bridge's ClientTlsOptions struct using a function pointer pattern, similar to the existing grpc_override_callback:

typedef struct ClientTlsOptions {
    // ... existing fields ...
    // Optional callback for dynamic cert resolution
    CertResolverCallback *cert_resolver;
} ClientTlsOptions;

The C bridge would wrap the callback in a ResolvesClientCert adapter struct.

References

• Support dynamic client certificate resolution (ResolvesClientCert) #1340 (review discussion)
• crates/sdk-core-c-bridge/src/client.rs