cmd/tsconnect: switch to TypeScript

Continues to use esbuild for development mode and building. Also
includes a `yarn lint` script that uses tsc to do full type checking.

Fixes #5138

Signed-off-by: Mihai Parparita <mihai@tailscale.com>

cmd/tsconnect/src/index.ts

@@ -0,0 +1,26 @@
+// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import "./wasm_exec"
+import wasmUrl from "./main.wasm"
+import { notifyState, notifyNetMap, notifyBrowseToURL } from "./notifier"
+import { sessionStateStorage } from "./js-state-store"
+
+const go = new Go()
+WebAssembly.instantiateStreaming(
+  fetch(`./dist/${wasmUrl}`),
+  go.importObject
+).then((result) => {
+  go.run(result.instance)
+  const ipn = newIPN({
+    // Persist IPN state in sessionStorage in development, so that we don't need
+    // to re-authorize every time we reload the page.
+    stateStorage: DEBUG ? sessionStateStorage : undefined,
+  })
+  ipn.run({
+    notifyState: notifyState.bind(null, ipn),
+    notifyNetMap: notifyNetMap.bind(null, ipn),
+    notifyBrowseToURL: notifyBrowseToURL.bind(null, ipn),
+  })
+})