Support react-refresh and shared client/server types (#98)

- Adds support for react-refresh through `@pmmwh/react-refresh-webpack-plugin`. Updated webpack config to support this. Means entire app is no longer refreshed on changes, only individual components, and state is maintained.
- React refresh removes need for `google-apps-script-webpack-dev-server` package
- In client code, support for server function autocomplete through use of gas-client 1.0.0. Requires certain files to be typescript .ts files
- Remove need for "global" exports in main server file through updated gas-webpack-plugin

.github/workflows/integration-tests-extended.yaml

@@ -11,7 +11,7 @@ jobs:
         os: [macos-10.15, macos-latest, windows-latest]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
         node-version: [12, 14, 16]
-    timeout-minutes: 10
+    timeout-minutes: 11
     steps:
       - uses: actions/checkout@v2
       - name: Use Node.js ${{ matrix.node-version }}