Workspace switcher enhancements

Problem/Motivation

1. In case only few workspaces (for example less than or 6) workspaces are available, showing all workspaces is easier to interact with than showing only the user's workspaces.
2. Currently, the recent workspaces are expiring too fast for some users. Thus it makes sense to add an option that allows increasing the time until a workspace is cleared from the recents lists, or even allows disabling expiration.

Proposed resolution

Make the time for expiration of recent workspaces configurable on the settings form via a number. Allow setting it to 0 for no expiration. Also display all workspaces in case there is just a limited amount available (let's say 6 for now). This limit may be exposed on the settings form as well if required.

User interface changes

New field on the settings form of this module, which allows increasing/disabling the clearing of workspaces from the recents list.