[web] introduce reactions to inline sidebar

Summary:
introduce reactions to inline sidebar. Right now, going with a temporary solution of just showing the number of likes right now, but in a subsequent diff will be extending this to show more information about the reaction message

Depends on D5812

Linear Task: ENG-2409

Test Plan:
Please see the screenshot to see what "message likes" look like:

Reviewers: atul, tomek, rohan

Reviewed By: atul, tomek

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D5814