SUMMARY
Only remove trailing whitespaces from non-empty lines

STEPS TO REPRODUCE
When Kate saves a file, by default it will remove trailing spaces from a line, which is fantastic, but in combination with 1s autosave intervals, the cursor will very quickly jump to the beginning of the line, which can become frustrating.

OBSERVED RESULT
Cursor jumps to the beginning of the line, as the line consist only of whitespace and so is cleared.

EXPECTED RESULT
By ignoring lines containing only whitespace, this behaviour is accounted for.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: KDE Neon 5.27.7
KDE Plasma Version: 5.27.7
KDE Frameworks Version: 5.108.0
Qt Version: 5.15.10