[GCI] Parse runtime output of assert() message, make it clickable

Note: We can only handle absolute paths, I honestly think supporting
relative paths is out of scope. Too many (likely fragile) heuristics needed in
order to support this reliably.

Reviewers: KDevelop

Subscribers: KDevelop

Projects: KDevelop

Differential Revision: https://phabricator.kde.org/D751

BUG: 354695
FIXED-IN: 5.0.0