Implement serde traits for `tonic_types::Status`

## Feature Request

### Crates

tonic_types

### Motivation

I'm working with a gRPC API that uses both Well Known Types and Google's RPC types. I've setup the extern paths as such:

```
.google.protobuf=::pbjson_types
.google.rpc=::tonic_types
```

I'm trying to use `protoc-gen-prost-serde`, but it's failing to generate because some of the protobuf messages embed the Status type which does not implement deserialization. It's throwing this error:

```
the trait `Deserialize<'_>` is not implemented for `tonic_types::Status`
```

From what I've discovered, I can add a type attribute of `#[derive(serde::Serialize)]` to the types that I'm generating, but because I'm "linking" to the tonic_types library, I don't believe I can modify the `Status` type to support serialization without modifying upstream.

### Proposal

Have a feature for enabling the dependency on serde in the tonic_types crate.
I'm not a regular Rust programmer these days, so I'm probably not the best source of ideas.

### Alternatives

Would be super happy to hear any if I'm missing something!