Summary:
Fix https://github.com/facebook/flipper/issues/931
This is not how I would *like* to fix this, but it should do the job.
When the switch over to AndroidX was made, the overall abstraction
started to leak and we really need to remodel this in its entirety.
There's also the question of whether we want to support both support
fragments and AndroidX fragments or not. Right now it's kinda-sorta
supported but only under some circumstances, which is not great.
I also added some more defensive try/catches as there's some unsafe casting
involved and future changes may break this causing the entire layout to disappear.
Change Log: Fix support for AndroidX fragments in Layout Inspector.
Pull Request resolved: https://github.com/facebook/flipper/pull/957
Test Plan:
Changed the sample app to include some AndroidX fragments and they
now show up (again) in the view hierarchy:

Tested internally that FB4A fragments show up again, too:
{F233098198}
Reviewed By: mweststrate
Differential Revision: D20792503
Pulled By: passy
fbshipit-source-id: 7030b897ab547d1e8803b7f0d7aaa34263cfaed2