Isolate workspaces

### Problem

Currently, dock shows apps opened on all workspaces. However, this does not fit in to the concept of '1 workspace 1 task'.

From the 'studying workspace', a user can still directly access the browser window in the entertainment workspace by clicking on the browser icon in dock. This is not desirable as it cannot maintain the principle that 'what happens in this workspace stays in this workspace' and significantly weakens workspace separation.

This also causes a lot of confusion to the user as to what workspaces are supposed to be and hurts the 'switching workspaces as alternative to minimizing apps' argument (if workspaces are not isolated, that means tasks can be and should be mixed between workspaces, i.e. the user can have entertainment and productivity in a single workspace, and that means the argument for minimizing apps is valid).

### Proposal

1. Only show apps opened in that workspace in dock. Hide apps from all other workspaces. If the user tries to open an app that is not in that workspace and can only have one instance of, switch to the workspace where the opened window is in (and bring that window to focus).
2. In the spirit of 'what happens in a workspace stays in that workspace', apps should open in whichever workspace its icon was clicked on. That is, if users open an app in workspace 2 and switches to workspace 1 before the app window is opened, the app window should open in workspace 2.
3. Inform new users of this workflow in the onboarding experience, as this is likely to be drastically different from what they are used to.

### Prior Art (Optional)

The Dash to Dock Gnome shell extension has an identical option where only apps from that particular workspace is shown in the dock.