feat(prost-build): add affixes support

[Antonito]

Adds the ability to specify a prefix and/or suffix to generated types, allowing users to transform generated type names (ex: MyMessage -> MyMessageProto)

This is done by exposing two new APIs in prost-build:

• package_type_name_suffix
• package_type_name_prefix

which allows users to specify affixes on a per-package basis.

For ease of use, also provides:

• type_name_suffix
• type_name_prefix

to impact the current package.

// build.rs
prost_build::Config::new()
  .type_name_suffix("Proto")
  .compile_protos(...);

// same as
prost_build::Config::new()
  .package_type_name_suffix([(".", "Proto")])
  .compile_protos(...);

Example:

// external_package.proto
syntax = "proto3";

package external_package;

message ExternalMessage {
    string name = 1;
}

// type_name_imports.proto
syntax = "proto3";

package type_name_imports;

import "google/protobuf/timestamp.proto";
import "external_package.proto";

message ImportTestMessage {
    google.protobuf.Timestamp created_at = 1;
    external_package.ExternalMessage external_msg = 2;
}

// build.rs
prost_build::Config::new()
  .type_name_suffix("Proto")
  .package_type_name_suffix([(".external_package", "ABC")])
  .compile_protos(
    &[
      src.join("type_name_imports.proto"),
      src.join("external_package.proto"),
    ],
    &[src.clone(), src.join("include")],
  );

Generated code:

// This file is @generated by prost-build.
#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
pub struct ExternalMessageABC {
    #[prost(string, tag = "1")]
    pub name: ::prost::alloc::string::String,
}

// This file is @generated by prost-build.
#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
pub struct ImportTestMessageProto {
    #[prost(message, optional, tag = "1")]
    pub created_at: ::core::option::Option<::prost_types::Timestamp>,
    #[prost(message, optional, tag = "2")]
    pub external_msg: ::core::option::Option<
        super::external_package::ExternalMessageABC,
    >,
}