Add a protobuf item template (#10125)

Author: John Luo

src/ProjectTemplates/Web.ItemTemplates/content/Protobuf/.template.config/dotnetcli.host.json

@@ -0,0 +1,3 @@
+{
+  "$schema": "http://json.schemastore.org/dotnetcli.host"
+}

src/ProjectTemplates/Web.ItemTemplates/content/Protobuf/.template.config/template.json

@@ -0,0 +1,44 @@
+{
+  "$schema": "http://json.schemastore.org/template",
+  "author": "Microsoft",
+  "classifications": [
+    "Web",
+    "gRPC"
+  ],
+  "name": "Protocol Buffer File",
+  "generatorVersions": "[1.0.0.0-*)",
+  "description": "A protocol buffer file for describing messages and services for gRPC.",
+  "tags": {
+    "language": "",
+    "type": "item"
+  },
+  "groupIdentity": "Microsoft.Web.Grpc.Protobuf",
+  "precedence": "100",
+  "identity": "Microsoft.Web.Grpc.Protobuf",
+  "shortname": "proto",
+  "sourceName": "protobuf",
+  "primaryOutputs": [
+    {
+      "path": "protobuf.proto"
+    }
+  ],
+  "defaultName": "protobuf",
+  "symbols": {
+    "HostIdentifier": {
+      "type": "bind",
+      "binding": "HostIdentifier"
+    }
+  },
+  "postActions": [
+    {
+      "condition": "(HostIdentifier != \"dotnetcli\" && HostIdentifier != \"dotnetcli-preview\")",
+      "description": "Opens protobuf.proto in the editor",
+      "manualInstructions": [],
+      "actionId": "84C0DA21-51C8-4541-9940-6CA19AF04EE6",
+      "args": {
+        "files": "0"
+      },
+      "continueOnError": true
+    }
+  ]
+}

src/ProjectTemplates/Web.ItemTemplates/content/Protobuf/protobuf.proto

@@ -0,0 +1 @@
+syntax = "proto3";