Fix highlighting when editing in patch review

Summary:
Problems:

• removing markers in foreach loop lead to crash (BUG 380125)
• highlighting when editing in patch review was broken
• reloading would stop the highlighting

Fixes:

• textInserted/textRemoved signals only send line-by-line (or character-by-character) changes and there are extra signals for newline insertion/removal. The patch reflects this mechanism.
• Redo the highlighting when the document is reloaded.
• Remove one of the duplicated lists of ranges (mainly to improve maintainability).

Persisting Issue:

• possible dangling mark when removing the "wrong" newline from a set of newline-only-lines changes.

BUG: 380125

Test Plan:

• tested text insertion, text removal and mark clicking and the combination of those with (mostly) consistent results for a git diff

Reviewers: KDevelop, apol

Reviewed By: KDevelop, apol

Subscribers: kdevelop-devel

Differential Revision: https://phabricator.kde.org/D6398