Show last selected color scheme in color scheme picker

[websterzh]

Describe the bug
On the preferences - color schemes page, the currently-using color scheme is not shown on the selector. It seems to be inconsistent with other selections where they have their currently selected option shown on the selector.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Preference - Color Schemes'
2. Currently selected option is not shown on the selector for both 'VATprism Color Schemes'.

Expected behavior
There should be something shown on the 'VATprisim Color Schemes' selector.

Screenshots

Additional context

• OS: MacOS 11.6
• Hardware Platform: Apple M1

[marvk]

This is working as intended right now, but it would be a better user experience if the last selected color scheme was shown in the picker, maybe with a modified tag if the color scheme was modified after being selected.