Support TLS reloading on gRPC server

[shuiyisong]

What type of enhancement is this?

Tech debt reduction

What does the enhancement do?

previous: #3336

We've support configuring TLS on gRPC server, but the auto reload is not supported yet, and it's inconsistency with MySQL and PostgreSQL server.

greptimedb/src/servers/src/grpc/builder.rs

Lines 170 to 175 in 2971052

	if tls_option.watch {
	return Err(Error::NotSupported {
	feat: "Certificates watch and reloading for gRPC is not supported at the moment"
	.to_string(),
	});
	}

Let's enable auto reloading on gRPC server too.

Implementation challenges

No response

[irenjj]

I'd like to take it.

[shuiyisong]

I'd like to take it.

Have fun 🤩

[irenjj]

hi, @shuiyisong , it seems for tonic based gRPC, reloading TLS config requires restarting the service

[shuiyisong]

@irenjj OK, it's more complicated then I originally thought. We'll dig into this problem later. Removing you from assignees from now, but you are always free to explore this problem. :P