[RFC] Defuse KateMainWindow::showModOnDiskPrompt

Summary:
BUG:351443
BUG:375725

Test Plan:
Fixed in a way as suggested in bug report.

Expected Results:
Exit without asking (file was not edited since last time in kate, so there is no info to lose)

This dialog is for me pretty confusing and annoying.

• In which case may that question (without this patch) useful?
• Why should I reload a file when I like to close Kate?
• Click "Ignore" you will asked again, where you can overwrite the file on disk. The opposite from your first intend.
• Click "Diff" keeps the dialog the focus with the result that you can't scroll in the loaded diff. With dark theme is it hard to read too
• You can end in some "endless" dialog boxes

So, how about to remove that dialog?

BUG:375725 Same issue, different request

Reviewers: Kate, cullmann

Reviewed By: Kate, cullmann

Subscribers: cullmann, ngraham, kwrite-devel, Kate

Tags: Kate

Differential Revision: https://phabricator.kde.org/D19397