[web] move reaction message action type logic into useSendReaction

Summary:
This diff brings in the logic which determines if we are reacting or unreacting to a message into the useSendReaction hook. I don't know why we didn't do this initially, but this diff resolves this and will make it so we don't need to copy/paste this logic when we call useSendReaction with the InlineEngagement

Depends on D8710

Test Plan: flow and confirmed that I can still react and unreact to messages

Reviewers: atul, kamil

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8711