Feature freeze exception (or not) for "Advanced Power Settings" QML port

[Jakob Petsovits]

Hi team,

I rebased my earlier QML port of kcm_powerdevilglobalconfig to resolve outstanding issues and merge it into the "Energy Saving" KCM (that's also a QML KCM now) as a child page. Feature freeze or not, it had to be done anyway eventually.

MR link: https://invent.kde.org/plasma/powerdevil/-/merge_requests/214

Recent quote from Nate, who subsequently also approved the MR and suggested emailing plasma-devel:

> It's a big change so it's covered by the feature freeze, but it's reasonable to ask for an exception since this work was started a while ago and it's in a very advanced state.

So I'd like to open it up to the mailing list whether it makes sense to merge this now or instead wait until 6.1.

Pro:
* Majority of the patch got reviewed and tested prior to feature freeze.
* No new features are actually introduced, but UI & phrasing tweaks provide marginal improvements.
* Helps with the ongoing effort of "Flattened navigation with logically combined KCMs" [1].
* There's a bug on Bugzilla (following from internal discussion?) for merging KCMs [2], mostly addressed by this MR.
* Might help with other bugs such as [3] or [4], 

Contra:
* Larger patch and hasn't been part of beta 1 for widespread testing.
* I think there's still a mnemonic regression even outside of my auth-broken setup, not sure how difficult to fix.
* Might not want to set a precedent for feature freeze exceptions.
* [Any additional concerns you might have.]

Let me know what you think, I'm fine either way. Cheers,
- Jakob

[1] https://invent.kde.org/plasma/systemsettings/-/issues/15
[2] https://bugs.kde.org/show_bug.cgi?id=450276
[3] https://bugs.kde.org/show_bug.cgi?id=449254
[4] https://bugs.kde.org/show_bug.cgi?id=459081