Quick open: support also line number notions "#Lll", "#nll", "#ll"

Summary:
Pasting a path extracted from a repo web link on cgit, github, gitlab, or lxr
to Quick Open currently needs manual editing of the line number notion.
This patch allows to open them directly.

Reviewers: kfunk, KDevelop, kwrite-devel

Subscribers: kfunk, kdevelop-devel

Differential Revision: https://phabricator.kde.org/D4110