Extend character clipping by grouping it with spaces

Summary:
Group spaces following any non-wide character with the character. This
allows for rendering ambiguous characters with wide glyphs without
clipping them. Characters are still clipped when followed by another
visible character.

BUG 401298

Test Plan:

• Display: ⛰ ⛩

and/or:

• Install Font Awesome or other font with square icons in Private Use Area
• Pick some icons using KCharSelect or similar tool (or copy this:      )
• Put space after each icon and display them in Konsole

Actual result:
Only left half of icons is rendered
Expected result:
Full icon should be rendered (it can be clipped on top or bottom though)

Reviewers: Konsole, hindenburg

Reviewed By: Konsole, hindenburg

Subscribers: hindenburg, konsole-devel

Tags: Konsole

Differential Revision: https://phabricator.kde.org/D18784