Feature Request: Add-ons / Extensions

### What

I love Studio, but I think it is missing a gem: App extensions (or add-ons).

That would require exposing some parts of the UI, like the menu or section under the Overview tab (actually each tab), and allowing extensions to hook into it.

### Why

Extensibility of a tool like Studio is key for people with intense use, and I think that a feature like this will spread its adoption.

I think the more we can develop extensions over Studio, the more it will be embraced by the community.

I would like to create an add-on to simply create site notes, or an extension that has access to wp-cli and can create DB back-ups with `wp db import/export`.

Why not think bigger and allow us to create our own extension for push / pull to our own server? I understand there is already an area that lets you do that with wp dot com, and maybe there is a commercial gain there, but if someone is able to develop an extension, I'm pretty sure it already has a favourite hosting.

### How

_No response_