Allowing two-finger pitch with cooperative gestures in fullscreen

[SnailBones]

Follow up to #12058, which fixed cooperative gestures dragging behavior and warning message incorrectly appearing in fullscreen on mobile (#11635). A small oversight was that the cooperative gestures still applied to touch pitch, making them require 3 instead of 2 fingers, which causes two finger interactions to instead pan the map. This PR makes fullscreen behavior consistent with maps without cooperative gestures.

Also adds previously missing tests for touch pitch.

Here I test a two-finger drag on Android:

Before fix:

pitch-broken.webm

After fix:

pitch-fixed.webm

Launch Checklist

• briefly describe the changes in this PR
• include before/after visuals or gifs if this PR includes visual changes
• write tests for all new functionality
• manually test the debug page
• apply changelog label ('bug', 'feature', 'docs', etc) or use the label 'skip changelog'
• add an entry inside this element for inclusion in the mapbox-gl-js changelog: <changelog>Fix incorrectly requiring three finger drags to change pitch with cooperative gestures while in fullscreen.</changelog>

[avpeery]

@SnailBones Unfortunately, the fullscreen api isn't supported on iPhones. I'll reach out to the team to see if anyone has an iPad to test iOS support. (see MDN). The solution makes sense though and tests look good!

[avpeery]

LGTM! Thanks for testing on another touch screen @SnailBones