Explain how permissions work

[hanaral]

@cassidyjames Here is a proper continuation from our dialogue on #148

Problem

(This is an attempt to make my previous issue more addressable by itself)

The current permissions tab is app-first, which isn't too much of an issue. However, the way that it is presented and explained isn't universally informative enough. It also makes it difficult to translate in to other languages that don't have so many native words that rely on prev. knowledge of tech. stuff.
It's also inconsistent with the rest of the system which does a good job of explaining things in a [relevant verb] [relative subject] fashion.

Proposal

Since it's difficult to cram full explanations below every item, switch to a similar page layout to Firmware, Bluetooth etc. and add an explanation to the top of the view of what permissions are and how given/revoked and can be asked for by apps. The actual permissions on the list can then be slimmed down by changing their subtitles to only be a desc. of what the item is associated with rather than a explanation of what toggling it does (could be a separate PR)

Prior Art

Crude mockup: