Prevent crashes when creating new workspaces with a YAML config

[dalyIsaac]

This PR fixes a critical crash which would occur when creating a workspace during runtime (after startup).

The issue was that a TreeLayoutPlugin event was not enqueued onto the WinUI dispatcher.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 80.56%. Comparing base (bd17c2c) to head (3138c6d). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1068 +/- ## ======================================= Coverage 80.56% 80.56% ======================================= Files 283 283 Lines 12409 12412 +3 Branches 1432 1432 ======================================= + Hits 9997 10000 +3 Misses 2227 2227 Partials 185 185 ```

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