Theme: update to sync with gtk Adwaita

- consistent OSD colors
- consistent fg/bg colors
- updated rounded corners
- switches

Fixes #841
4 jobs for !584 with wip/jimmac/sync-with-adwaita in 3 minutes and 50 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Review
passed #335424
check_commit_log

00:00:26

 
  Build
passed #335425
build

00:02:11

 
  Test
passed #335426
test

00:01:12

passed #335427
test-pot

00:01:12