Make JX.Tooltip more conservative about positioning
Summary:
Fixes T10687. Fixes T12064.
- Primarily, adds a margin around the edge of the screen for the purposes of aligning the tooltip.
- Also, tries to flip the tooltip if it can (e.g., if the tooltip normally goes east, try west first), then tries other positions exhastively.
Test Plan:
{F2309363}
{F2309364}
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T12064, T10687
Differential Revision: https://secure.phabricator.com/D17145