Add typings to package.json in packages (#18640)

Fixes Go to definition in webstorm

packages/grafana-data/package.json

@@ -40,5 +40,6 @@
     "rollup-plugin-visualizer": "0.9.2",
     "sinon": "1.17.6",
     "typescript": "3.5.3"
-  }
+  },
+  "types": "src/index.ts"
 }

packages/grafana-runtime/package.json

@@ -39,5 +39,6 @@
     "rollup-plugin-typescript2": "0.19.3",
     "rollup-plugin-visualizer": "0.9.2",
     "typescript": "3.5.3"
-  }
+  },
+  "types": "src/index.ts"
 }

packages/grafana-toolkit/package.json

@@ -98,5 +98,6 @@
   },
   "_moduleAliases": {
     "puppeteer": "node_modules/puppeteer-core"
-  }
+  },
+  "types": "src/index.ts"
 }

packages/grafana-ui/package.json

@@ -82,5 +82,6 @@
     "rollup-plugin-typescript2": "0.19.3",
     "rollup-plugin-visualizer": "0.9.2",
     "typescript": "3.5.3"
-  }
+  },
+  "types": "src/index.ts"
 }