fix(MessageReaction): Prevent event double fire from uncached messages

[Jiralite]

Please describe the changes this PR makes and why it should be merged:
This should resolve #5063.

The problem was that the manual call to the handler was running side-by-side with the payload received from Discord, resulting in the event firing twice (and the cache check being redundant). In this case, I added a new parameter called fromStructure to the handler (which is called only from the structure) and removed the existing cache check! This should return the object instead of firing the event when called from the structure and will allow the object to be received without firing the event, which in turn will let the event be fired only from a payload received from Discord.

Status and versioning classification:

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

[SpaceEEC]

If the message is not partial and the request goes through before the gateway event comes in, the reaction add event will not be emitted at all.

I don't really have a good solution for this at hand though. 😅

Stale

[vladfrangu]

This looks fine, however isn't this an issue?

Stale