Add opt-in complementary debug-token colour scheme

[ejrshadbolt]

ദ്ദി◝ ⩊ ◜.ᐟ ♡

[RedCMD]

@ejrshadbolt interesting idea
how come you want to change the colours?

this only changes the thumbnail colour in the suggestions picker btw
it doesn't actually change the rendering colour

these 'defaultThemeColor' tokens don't actually come from the built-in themes
but from within VSCode itself
https://github.com/microsoft/vscode/blob/a0efe49e539835660e16b19a341bd63a4fe50308/src/vs/workbench/services/themes/common/colorThemeData.ts#L823-L848

(tho it seems the 2026 Dark and Light High Contrast themes do actually have them aswell)