gears: update colours
As suggested in this fedi post. The colours for all gear applications have been updated.
The new gears' colours can be enabled via -Duse-rainbow-gears-colors=disabled
. The default is to still use the old colours.
This also adds a warning for users that the default behavior of gears' colours may change in the future, and a tool that users who need to know the colours of the gears can use to query the gears' colours.
Edited by Ella Stanforth