[web] Use shared logic to display tooltips

Summary: This diff introduces logic shared between tooltips and determining its positions.

Test Plan:
Check if timestamp tooltip is displayed below the message. Check if tooltip is displayed above message and creating sidebars is possible
Check various scenarios to see if tooltips are displayed correctly.

Reviewers: ashoat, palys-swm

Reviewed By: ashoat, palys-swm

Subscribers: zrebcu411, Adrian, atul, subnub

Differential Revision: https://phabricator.ashoat.com/D845