tools: Use Google.Api.Generator from a dotnet tool

.config/dotnet-tools.json

@@ -25,6 +25,12 @@
       "commands": [
         "generate-sbom"
       ]
+    },
+    "Google.Api.Generator": {
+      "version": "1.5.0",
+      "commands": [
+        "google-gapic-generator"
+      ]
     }
   }
 }

toolversions.sh

@@ -13,12 +13,6 @@ declare -r DOTCOVER_VERSION=2019.3.4
 declare -r REPORTGENERATOR_VERSION=2.4.5.0
 declare -r PROTOC_VERSION=3.25.2
 declare -r GRPC_VERSION=2.60.0
-if [[ $GAPIC_GENERATOR_VERSION == "" ]]
-then
-  declare -r GAPIC_GENERATOR_VERSION=v1.4.32
-else
-  echo "Using GAPIC generator override: ${GAPIC_GENERATOR_VERSION}"
-fi
 
 # Tools that only run under Windows (at the moment)
 declare -r DOTCOVER=$TOOL_PACKAGES/JetBrains.dotCover.CommandLineTools.$DOTCOVER_VERSION/tools/dotCover.exe
@@ -102,32 +96,20 @@ install_microgenerator() {
 
   # If the CSHARP_GENERATOR_DIR env variable is set
   # we use that as the generator root dir.
-  if [[ "$CSHARP_GENERATOR_DIR" != "" ]]
-  then
-    declare -r GENERATOR_ROOT=$CSHARP_GENERATOR_DIR
-  else
-    declare -r GENERATOR_ROOT=$REPO_ROOT/gapic-generator-csharp
-  fi
-
-  export GAPIC_PLUGIN=$GENERATOR_ROOT/Google.Api.Generator/bin/Release/net6.0/$RUNTIME/publish/Google.Api.Generator$EXTENSION
-
   if [[ "$CSHARP_GENERATOR_DIR" != "" ]]
   then
     echo "Skipping microgenerator fetch: an existing directory for the generator has been specified"
-  elif [ -d $GENERATOR_ROOT ]
-  then
-    git -C $GENERATOR_ROOT fetch -q --tags
-    git -C $GENERATOR_ROOT checkout -q $GAPIC_GENERATOR_VERSION
+    (cd $CSHARP_GENERATOR_DIR; \
+     dotnet restore -v quiet; \
+     dotnet publish -v quiet -nologo -clp:NoSummary -c Release --self-contained --runtime=$RUNTIME Google.Api.Generator)
+    export GAPIC_PLUGIN=$CSHARP_GENERATOR_DIR/Google.Api.Generator/bin/Release/net6.0/$RUNTIME/publish/Google.Api.Generator$EXTENSION
   else
-    git clone https://github.com/googleapis/gapic-generator-csharp $GENERATOR_ROOT -q
-    git -C $GENERATOR_ROOT checkout -q $GAPIC_GENERATOR_VERSION
+    # We don't just use "dotnet tool restore", as we need it installed in a specific
+    # path in order to access the executable directly (as it's a protoc plugin).
+    rm -rf gapic-generator
+    dotnet tool install Google.Api.Generator --tool-path gapic-generator > /dev/null
+    export GAPIC_PLUGIN=$REPO_ROOT/gapic-generator/google-gapic-generator$EXTENSION
   fi
-
-  # The dotnet restore step isn't generally required when cloning from elsewhere,
-  # but helps when running a local generator. (It does no harm even when not required.)
-  (cd $GENERATOR_ROOT; \
-   dotnet restore -v quiet; \
-   dotnet publish -v quiet -nologo -clp:NoSummary -c Release --self-contained --runtime=$RUNTIME Google.Api.Generator)
 }
 
 install_grpc() {