Freeze string literals by default

[mvz]

Summary

Add # frozen_string_literal: true comments to all files and fix what breaks.

Details

• Re-enable Style/FrozenStringLiteralComment cop
• Autocorrect Style/FrozenStringLiteralComment offenses
• Make CommandMonitor output collection methods work with frozen string literals
• Restore spec for unfrozen input to command

Motivation and Context

Ruby 3.4 will freeze string literals by default.

How Has This Been Tested?

I ran specs and cukes.

Types of changes

• Internal change (refactoring, test improvements, developer experience or update of dependencies)

Checklist:

• I've added tests for my code
• My change requires a change to the documentation.
• I have updated the documentation accordingly.