Tweak replacement logic and logging per requirements

[ssciolla]

We discussed some scenarios with the tool tab replacement and defined the following requirements:

• What should happen if the source tool is already hidden?
  • No replacement action needed
• What should happen if the target tool is already available?
  • No action needed
• What should happen if both tools are on the site?
  • Hide the source tool, and it will be deleted in the future
• What happens if we roll back?
  • Log courses where both tools are enabled?