Bash: fix comments after escapes

Summary:
BUG: 418876

Comments were not highlighted after an escaped space, but this should only occur in commands.
This is corrected: outside of a command, comments are highlighted after an escaped space.

Reviewers: Framework: Syntax Highlighting, dhaumann, cullmann

Reviewed By: Framework: Syntax Highlighting, cullmann

Subscribers: kwrite-devel, kde-frameworks-devel

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D29354