Prost Crate Naming Conventions

Wanted to start a discussion around the current naming conventions in the prost rules provided by rules_rust.

The prost rules set the crate name to the name of the proto_library that is being compiled.
This approach is very prone to clashes e.g. the following folder structure:
```
/src
/protobuf
service1/
/models
models.proto
service2/
/models
models.proto
```
In this folder structure the common way to name the proto_library target would be models_proto (Which is the convention that gazelle uses) but that causes issues if there is a consumer that needs both service1/models and service2/models .

I think it makes sense to change the naming conventions or make them configurable since this is a very likely issue when you have a repo with a large protobuf codebase.

Options:
* Change the naming convention to include the package path in the crate name
* The example above would end with `src_protobuf_service1_models_models_proto` and `src_protobuf_service2_models_models_proto`
* Make the convention configurable on the prost toolchain
* The toolchain could provide a `crate_naming_convention` which accepts `proto_name` and `package_name` where `proto_name` would keep the current convention but `package_name` would include the package path in the crate name