Move settings level selector into sidebar

[DL6ER]

What does this implement/fix?

Move settings level selector into the sidebar instead of the settings page header

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[DL6ER]

Rebased on latest development-v6

[github-actions]

Conflicts have been resolved.

[yubiuser]

What's about the idea we discussed internally: getting rid of the setting levels at all? We wanted to keep the level indicators (wrench/cog), but remove the selector and show everything always

[DL6ER]

Further discussion going on, I will make this a draft and remove the requested review.

[DL6ER]

Superseded by #2882