Tiles LOD: load and render based on zoom when displayed

[astojilj]

• Land [core] Limit pitch based on edge insets. Fix max Z calculation in getProjMatrix. #15195
• Unit test verifying that LOD cover covers previously returned by tileCover for different states.
• Verify no performance drawbacks in standard mode. LOD is not active if there are no inset set and pitch <= 60.
• Current limit of 70 degrees is likely to be lowered to 68, depending on performance measurements.

Attached video shows 70 degree pitch on iPadMini2: ipadmini270degpitch.mp4.zip

Fixes #9037, #15163

[1ec5]

FYI, the iOS map SDK is currently using this constant to fake a tilted annotation view specifically for the user dot / user puck:

mapbox-gl-native/platform/ios/src/MGLAnnotationView.mm

Lines 162 to 165 in b6dd995

	// The pitch intensity represents how much the map view is actually pitched compared to
	// what is possible. The value will range from 0% (not pitched at all) to 100% (pitched as much
	// as the map view will allow). The map view's maximum pitch is defined in `mbgl::util::PITCH_MAX`.
	CGFloat pitchIntensity = pitch / MGLDegreesFromRadians(mbgl::util::PITCH_MAX);

Though something like mapbox/ios-sdk-examples#111 (comment) would be a much sounder approach long-term: #10498.

[astojilj]

Update:
@arindam1993 is planning to implement this first in mapbox-gl-js.