Add close button to close preview debug window, #PG-3550

[AltamashShaikh]

Description:

Added close button to close preview debug window Fixes: #PG-3550

Review

• [ ] Functional review done
• [ ] Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• [ ] Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• [ ] Security review done
• [ ] Wording review done
• [ ] Code review done
• [ ] Tests were added if useful/possible
• [ ] Reviewed for breaking changes
• [ ] Developer changelog updated if needed
• [ ] Documentation added if needed
• [ ] Existing documentation updated if needed

[AltamashShaikh]

current page intended, or should it disable preview mode entirely? Not sure about expected logic. Are we confident this is correct, or need clarification?

@araichyk We initially thought that we just need to add a close button, as closing the debug mode would require an API call from the browser and I don't think that would be possible.