Implement last opened functionality (#4633)

* Implement last opened functionality

Fixes https://github.com/cdr/code-server/issues/4619

* Fix test temp dirs not being cleaned up

* Mock logger everywhere

This suppresses all the error and debug output we generate which makes
it hard to actually find which test has failed.  It also gives us a
standard way to test logging for the few places we do that.

* Use separate data directories for unit test instances

Exactly as we do for the e2e tests.

* Add integration tests for vscode route

* Make settings use --user-data-dir

Without this test instances step on each other feet and they also
clobber your own non-test settings.

* Make redirects consistent

They will preserve the trailing slash if there is one.

* Remove compilation check

If you do a regular non-watch build there are no compilation stats so
this bricks VS Code in CI when running the unit tests.

I am not sure how best to fix this for the case where you have a build
that has not been packaged yet so I just removed it for now and added a
message to check if VS Code is compiling when in dev mode.

* Update code-server update endpoint name

test/unit/node/proxy_agent.test.ts

@@ -1,11 +1,15 @@
 import { shouldEnableProxy } from "../../../src/node/proxy_agent"
-import { useEnv } from "../../utils/helpers"
+import { mockLogger, useEnv } from "../../utils/helpers"
 
 describe("shouldEnableProxy", () => {
   const [setHTTPProxy, resetHTTPProxy] = useEnv("HTTP_PROXY")
   const [setHTTPSProxy, resetHTTPSProxy] = useEnv("HTTPS_PROXY")
   const [setNoProxy, resetNoProxy] = useEnv("NO_PROXY")
 
+  beforeAll(() => {
+    mockLogger()
+  })
+
   beforeEach(() => {
     jest.resetModules() // Most important - it clears the cache
     resetHTTPProxy()