Add support to filter out folders and tasks by assignment

[fabiaserra]

Changelog Description

This adds a toggle in the Launcher, Workfile Manager and a few other widgets that show a folder hierarchy to filter out the folders and tasks shown by whether the user has it assigned or not:

Launcher

With filter

Without filter

Creator

Workfile manager

Scene Inventory

Additional info

~~The next step would be to also filter out the tasks by whether they are assigned or not~~ Done here https://github.com/ynput/ayon-core/pull/622/commits/61870650d8911c09393663047a96183a6ec638b5

Testing notes:

1. Open the launcher, workfile manager, creator, scene manager...
2. Check that a "Show my assignments only" toggle shows up and that when checked, only the folders and tasks that you have assigned show up