This PR adds support for iOS 14 in Xen HTML.

Other notable changes:

Fixed an issue where widgets didn't show up correctly when rotating on iPad
Apple's stock 'Add widget' flow is now used for adding foreground widgets
BatteryManager and preferences can now run in the Simulator
Loading components now mostly done in the Loader, rather than relying on the platform, to ensure load order is always correct
XenInfo is fully disabled on iOS 14, and will be phased out soon across all iOS versions (except iOS 9)
Added some extra stability checks into widgetinfod
All work was done without a jailbroken device, using the iOS Simulator

Related tickets:

Matchstic / Xen-HTML

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