Properly handle incomplete selection in RegionCommands

[SirYwell]

Overview

Fixes #3387

Description

There are 2 problems here:

1. Without the Confirm annotation, we never check if the selection is present. The changed commands all work on regions and should therefore also properly handle confirmation.
2. Our custom binding returns null instead of throwing IncompleteRegionException. I didn't find any reason for this binding to exist, so I think removing it make the most sense.

Submitter Checklist

• Make sure you are opening from a topic branch (/feature/fix/docs/ branch (right side)) and not your main branch.
• Ensure that the pull request title represents the desired changelog entry.
• New public fields and methods are annotated with @since TODO.
• I read and followed the contribution guidelines.