feat(Presence/Game): multiple activities and custom status

[SpaceEEC]

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

This PR backports #3661 and #3703 by adding support for multiple activities.
This PR also backports #3353 by adding emoji, createdAt, and createdTimestamp to Game.

I removed the duplicated code in Presence by putting the initializing part into the update method.

The hack using MessageReaction is a bit ugly, but I couldn't come up with anything better.

Status

• 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

Semantic versioning classification:

• This PR changes the library's interface (methods or parameters added)
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
• This PR only includes non-code changes, like changes to documentation, README, etc.