taskmanager: Indicate which tasks belong to which desktops when windows on all desktops are shown

When sorting tasks by desktop and not filtering by desktop, it can be
very difficult to determine which task is on which desktop, which can
make it difficult to figure out which window you want to select.

This commit adds a badge to indicate the desktop id of a task on its
icon, and the background color is changed according to the desktop id.

FEATURE: 410453
2 jobs for !676 with FEATURE410453-desktop-id-badge in 5 minutes and 4 seconds (queued for 56 minutes and 56 seconds)
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