fix: propagate execArgv (#5510)

* Use fork instead of spawn

We no longer do in-place updating so no need for the spawn.  The
advantage of a fork is that it preserves flags like --prof which you can
use to profile code-server.

Also I am not sure the comment about not being able to reload in place
with fork was even true to begin with.

* Refresh heartbeat patch

Seems to have gotten out of date a little.

* Propagate execArgv to extension host

This will let us profile the extension host.

src/node/wrapper.ts

@@ -317,8 +317,7 @@ export class ParentProcess extends Process {
   }
 
   private spawn(): cp.ChildProcess {
-    // Use spawn (instead of fork) to use the new binary in case it was updated.
-    return cp.spawn(process.argv[0], process.argv.slice(1), {
+    return cp.fork(path.join(__dirname, "entry"), {
       env: {
         ...process.env,
         CODE_SERVER_PARENT_PID: process.pid.toString(),