Summary:
Since the core layout in RN is now assigning `left/right` to `start/end`, we need to tweak the text input handling as well:
1. We need to replace all left/right to start/end
2. For text inset padding, we need to manually flipped the padding in RTL situation.
Reviewed By: fkgozali
Differential Revision: D3670277
fbshipit-source-id: 442bead25af8548a85dd1f359aa5a799982d1185