Add Support for Scheduled Events

[Hok-2323]

General Troubleshooting

• [x] I have checked for similar issues.
• [x] I have updated to the [latest JDA version][download].
• [x] I have checked the branches or the maintainers' PRs for upcoming features.

Feature Request

Discord has added its own integrated event thing. Implement the 'Event' Feature from Discord.

Example Use-Case

Example code or use cases can't be mentioned here as wouldn't know how to integrate Bots with it.

[Yashar256]

I don't think Discord has actually documented the API for Events yet. Does JDA add not yet documented bot features?

[topi314]

jda does not besides that they are working on the bot api for events see: https://github.com/discord/discord-api-docs/pull/3586

the current api is not final and subject to change

[itsmefox]

discord/discord-api-docs#3586 got merged.

[Yashar256]

I'm almost done writing the necessary interfaces/documentation for this, I'll try to see if I can create a draft PR in a bit if anyone would like to help with implementing it.

[MinnDevelopment]

This is supported as of 5.0.0-alpha.22