[web] introduce getTooltipScreenOverflowRightCorrection function

Summary:
As I was doing some final tests for the ReactionTooltip, I noticed a scenario where the reaction tooltip for the most right reaction pill of a viewer message was overflowing off the screen if the tooltip was at its maxWidth. To address this I created a helper function which calculates the overFlow and shifts the tooltip x anchor point

Depends on D8859

Test Plan:
Please see the screenshots below

Before:

After:

Reviewers: atul, kamil

Reviewed By: kamil

Subscribers: ted, ashoat, tomek

Differential Revision: https://phab.comm.dev/D8860