[VSCode] Provide autocompletion for compiler configuration

vscode-extension/package.json

@@ -102,7 +102,17 @@
           "description": "Whether or not we should automatically start the Relay Compiler in watch mode when you open a project."
         }
       }
-    }
+    },
+    "jsonValidation": [
+      {
+        "fileMatch": "relay.config.json",
+        "url": "./src/json-schemas/relay-config-json.jsonc"
+      },
+      {
+        "fileMatch": "package.json",
+        "url": "./src/json-schemas/package-json.jsonc"
+      }
+    ]
   },
   "prettier": {
     "arrowParens": "avoid",

vscode-extension/src/json-schemas/package-json.jsonc

@@ -0,0 +1,9 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema",
+  "properties": {
+    "relay": {
+      "description": "Relay.js configuration",
+      "$ref": "./relay-config-json.jsonc"
+    }
+  }
+}