feature/add missing functionality (giuinktse7#8)

* Migrate from Avalonia 0.10.7 to Avalonia 11.0.8

* Fix name clash

* Fix bug: Disable custom CheckBox style

The CheckBox box was invisible when the CheckBox wasn't enabled

* Add necessary package for ItemsRepeater

* Update names & formatting

* Re-enable Locator.CurrentMutable.Register

Must call these for the rxui Router to work

* Bump to .NET 8.0

* Fix Avalonia 11 migration issues

* Update save items otb dialog

* Fix "Create new OTB"

* Add option to write modified appearances.dat

* Fix bugs with editing item properties

* Update docs

* Improve feedback of actions

- Progress bar
- Info message updates

* Fix view transition

Fix: Forgot to set the correct item category

Add search (giuinktse7#3)

Add handling of the expireStop appearance flag (giuinktse7#1)

Update README.md