Use the protoc build plugin in examples (#2171)

Motivation:

We now have a SwiftPM build plugin to generate code as part of the build
process, the examples should make use of it.

Modifications:

- Remove generated code for examples and update the generate script to
  stop genearting example code.
- Symlink protos from examples to the checked out location in the repo;
  this avoids some duplication and makes it easier to keep things
  up-to-date.
- Add a basic config to each example.
- Update CI to install protoc before building examples.

Result:

Better examples, less code.

Author: glbrntt

.github/workflows/pull_request.yml

@@ -42,7 +42,7 @@ jobs:
           MATRIX_LINUX_5_9_ENABLED: false
           MATRIX_LINUX_5_10_ENABLED: false
           MATRIX_LINUX_COMMAND: "./dev/build-examples.sh"
-          MATRIX_LINUX_SETUP_COMMAND: ""
+          MATRIX_LINUX_SETUP_COMMAND: "apt update && apt install -y protobuf-compiler && ./dev/build-examples.sh"
 
   examples-matrix:
     name: Examples

Examples/echo/Package.swift

@@ -21,9 +21,9 @@ let package = Package(
   name: "echo",
   platforms: [.macOS("15.0")],
   dependencies: [
-    .package(url: "https://github.com/grpc/grpc-swift.git", exact: "2.0.0-beta.3"),
-    .package(url: "https://github.com/grpc/grpc-swift-protobuf.git", exact: "1.0.0-beta.3"),
-    .package(url: "https://github.com/grpc/grpc-swift-nio-transport.git", exact: "1.0.0-beta.3"),
+    .package(url: "https://github.com/grpc/grpc-swift.git", branch: "main"),
+    .package(url: "https://github.com/grpc/grpc-swift-protobuf.git", branch: "main"),
+    .package(url: "https://github.com/grpc/grpc-swift-nio-transport.git", branch: "main"),
     .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0"),
   ],
   targets: [
@@ -34,6 +34,9 @@ let package = Package(
         .product(name: "GRPCNIOTransportHTTP2", package: "grpc-swift-nio-transport"),
         .product(name: "GRPCProtobuf", package: "grpc-swift-protobuf"),
         .product(name: "ArgumentParser", package: "swift-argument-parser"),
+      ],
+      plugins: [
+        .plugin(name: "GRPCProtobufGenerator", package: "grpc-swift-protobuf")
       ]
     )
   ]

Examples/echo/Sources/Generated/echo.grpc.swift

@@ -0,0 +1 @@
+../../../../dev/protos/examples/echo/

Examples/echo/Sources/Generated/echo.pb.swift

@@ -0,0 +1,7 @@
+{
+  "generate": {
+    "clients": true,
+    "servers": true,
+    "messages": true
+  }
+}

Examples/echo/Sources/Protos/echo

@@ -21,8 +21,8 @@ let package = Package(
   name: "error-details",
   platforms: [.macOS(.v15)],
   dependencies: [
-    .package(url: "https://github.com/grpc/grpc-swift.git", exact: "2.0.0-beta.3"),
-    .package(url: "https://github.com/grpc/grpc-swift-protobuf.git", exact: "1.0.0-beta.3"),
+    .package(url: "https://github.com/grpc/grpc-swift.git", branch: "main"),
+    .package(url: "https://github.com/grpc/grpc-swift-protobuf.git", branch: "main"),
   ],
   targets: [
     .executableTarget(
@@ -31,6 +31,9 @@ let package = Package(
         .product(name: "GRPCCore", package: "grpc-swift"),
         .product(name: "GRPCInProcessTransport", package: "grpc-swift"),
         .product(name: "GRPCProtobuf", package: "grpc-swift-protobuf"),
+      ],
+      plugins: [
+        .plugin(name: "GRPCProtobufGenerator", package: "grpc-swift-protobuf")
       ]
     )
   ]