Small improvements in some XML files

Summary:
Changes:

• Replace some unnecessary RegExpr rules with other rules.
• Use non-capturing groups in some regular expressions.
• Add ##Modelines in comments.
• Add folding for multi-line comments, add attribute region in element <comment>.
• Add column atributte in some rules.

Test Plan: make test

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/D24982