GT-2452 Add support for new page collection type

[levieggertcru]

This PR adds a new page type (page-collection) to the mobile content renderer.

Changes in this PR include:

• Add feature flag page collection to the renderer parser. Controlled by Firebase remote config.
• Add MobileContentRendererView and MobileContentRendererViewModel which now subclasses MobileContentPagesView. Wasn't necessary, but does move some specific logic for the renderer out of MobileContentPagesView and MobileContentPagesViewModel.
• Change name MobileContentPagesPage.swift to MobileContentRendererInitialPage.swift.
• Change name MobileContentPagesInitialPageConfig.swift to MobileContentRendererInitialPageConfig.swift.
• Add view and view model for the new page collection page.
• Removed CYOA page view factory, wasn't needed since those views are part of the mobile content page view factory.
• Added a horizontal padding of 16 points to content stacks.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.94%. Comparing base (414fdd9) to head (307cd4d).
Report is 16 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2425      +/-   ##
===========================================
+ Coverage    95.92%   95.94%   +0.01%     
===========================================
  Files           62       62              
  Lines         5323     5323              
===========================================
+ Hits          5106     5107       +1     
+ Misses         217      216       -1     

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