Summary:
Add a test case showing off a pressable sticky header to RNTester.
Note that this test case does not follow the styling of the other ScrollView Examples. I chose not to make it follow the styling because the existing examples need to be refactored later to not use custom buttons.
Changelog:
[General][Added] Add Pressable Sticky Header example to ScrollViewExamples in RNTester
Reviewed By: lunaleaps
Differential Revision: D29437827
fbshipit-source-id: 3ccee5df99bc6f00a04e1ecbd47fbe86b1eda4dc