Supply overwrite option to --file/-iL with warnings off

[drwetter]

When choosing --file or -iL warnings were set in any case to --batch which needs e.g. currently an interaction when do bacth scanning. This PR enables to supply WARNINGS / --warnings =off before so that the interaction is mot needed.

See also #2496.

Describe your changes

Please refer to an issue here or describe the change thoroughly in your PR.

What is your change about?

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Typo fix
• Documentation update
• Update of other files

If it's a code change please check the boxes which are applicable:

• For the main program: My edits contain no tabs and the indentation is five spaces
• I've read CONTRIBUTING.md and Coding_Convention.md
• I have tested this fix against >=2 hosts and I couldn't spot a problem
• I have tested this new feature against >=2 hosts which show this feature and >=2 host which does not (in order to avoid side effects) . I couldn't spot a problem
• For the new feature I have made corresponding changes to the documentation and / or to help()
• If it's a bigger change: I added myself to CREDITS.md (alphabetical order) and the change to CHANGELOG.md