Color widgets based on their project affiliation

Heavily tweaked the initial patch

This patch adds a checkbox in the KDevelop setting that allows KDevelop
to color the tabs (of the open files) and the project tree view depending
on their project affiliation

Initial patch by Sebastien Speierer, thanks a lot!

REVIEW: 123279
BUG: 269704
FIXED-IN: 5.0.0