Make the new header optional

[bastelfreak]

Use Case

With PE 2023.7.0 we've the following header:

In restricted environments we have to work with laptops. The display space isn't huge and the header is stealing a good portion of it. It there a chance to make it optional?

Describe the Solution You Would Like

Make the UI configureable to disable the header

Describe Alternatives You've Considered

A custom stylesheet would be really annoying.

Additional Context

I would have tried to provide a patch, but the repo is private.