Give immediate feedback when emoji reacting to an issuable

Compare the two experiences below:

Twitter	GitLab
twttr_favourite	CleanShot_20210812164512

Given the nature of reacting to an issue/epic/MR with an emoji, I believe we can give an immediate feedback response without having to wait for an API call to succeed. From https://simonhearne.com/2021/optimistic-ui-patterns/#optimistic-atomic-actions:

Note that the animation starts as soon as you click, giving an immediate feedback response. This happens separately and in parallel to the actual API call to log the action. Further to the instant animation, the API call is resilient to network failures. If the API call fails it is added to a queue to be retried later. Only if the API call fails multiple times is the action “undone” in the UI - the heart icon simply fades back to the unchecked state.