feat: Add ApplicationEmoji to EmojiResolvable and MessageReaction#emoji

[Moebits]

Please describe the changes this PR makes and why it should be merged:

When using typescript you can't react to a message with an ApplicationEmoji because EmojiResolvable lacks the type.

Edit: I also updated BaseGuildEmojiManager.js and added ApplicationEmoji to the MessageReaction#emoji getter.

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