Create action to jump to the current execution line in debug mode.

Summary:
Added new action called "Show Current Line" that will jump to the
execution position of the debugging program. This allows setting a
shortcut to it, while the previous workaround of clicking on the active
frame in the frame stack didn't.

FEATURE: 361411

Reviewers: #kdevelop, brauch

Reviewed By: #kdevelop, brauch

Subscribers: kossebau, brauch, kdevelop-devel

Tags: #kdevelop

Differential Revision: https://phabricator.kde.org/D14618