Adopt utility process for shared process and file watchers

[bpasero]

This is a follow up from #92164 and covers remaining work to eventually enable sandboxed renderers fully in Electron via app.enableSandbox().

This means that our shared process has to move away from a node.js enabled browser window to the new utility process.

Breaking down the usages today:

• extension management
• settings sync
• profiles
• terminals
• file watcher

Some initial thoughts:

• the shared process should probably just change to be a utility process as a first step
  • however, any code that relies on the browser window network stack instead has to leverage Electrons net APIs from the electron-main process to not loose proxy support
  • this can probably be done by implementing some kind of IRequestService that is backed by a main process service implementation
• any child process has to decide whether it wants to lift up to a utility process off the main process or remain inside the shared process

//cc @alexdima

[sandy081]

settings sync is safe to be removed as it does not use any non sandbox stuff like node apis.

[bpasero]

To clarify: we can still have a shared process in the end, I do not have strong feelings, but it would be node.js only and not electron browser enabled. I think the benefit of having another process offload work from the main process is still valid.

[sandy081]

One concern I have with shared process not having electron browser enabled is the network proxy and If we can enable request service to redirect to main as you mentioned, this shall be fine. But I am wondering how much load we gonna put on main and if that impacts perf.

[bpasero]

As far as I know, network load is handled from another utility process, so I think that should be fine, right @deepak1556 ?

[deepak1556]

Yes that is correct, the main process is only responsible for initiating the request from the JS thread, the actual work is done by the network utility process.

[Tyriar]

For the terminal part in shared proc, it just passes manages the pty host process and passing requests to/from it, so good there.

#153182 seems like a blocker to enabling utility processes though.

[bpasero]

@Tyriar does #133895 still apply?