feat: support for CUSTOM_STATUS activity type

[favna]

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

This PR covers the custom status Discord recently released to the public. The PR was initially created 4 months ago based on data mined data but now that custom statuses are in the public the PR should enter the merge track.

Evals performed with code changes:

---

Original post from 4 months ago:

This is an upcoming feature that has been data mined from the Canary client. Presumably these few lines are all that is needed since in ClientPresence the number gets matched to the indexOf the ActivityType constant and the new options are as follows:

{
    PLAYING: 0,
    STREAMING: 1,
    LISTENING: 2,
    WATCHING: 3,
    CUSTOM_STATUS: 4 // the newly added type
}

Example images after enabling the option, courtesy of a friend of mine who has it as I do not have it myself.

As an aside, there also seems to be an upcoming custom voice status however there is not sufficient enough information for that yet to suggest any code changes. That said, I can guarantee my friend and I will keep our eyes out and I'll be back with another PR if required for that.

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.

[favna]

Bumping this up as custom status is landing now

[vladfrangu]

The PR is incomplete @favna, see discord/discord-api-docs#1160 (comment)

Maybe it's time to add these too?

[favna]

With 5a62541 I believe the part of adding it to Activity structure at least is fully covered.

Edit: 8e88100 squashes the above 3 commits into 1 for a cleaner merge

[bensaine]

I have you tested this manually through the API? Seems like it is not covered for Bot use as of right now.
https://www.reddit.com/r/discordapp/comments/dm47sv/at_least_something_regarding_custom_status/f508crt/

[favna]

@fatplatapus that's correct it's not available for bots but that doesn't stop bots from getting this data for regular users. Ergo you see the image of message.author.activity offering the data. Logging data in the Activity class returns all the added data from the API.

A good remark but note that it is also covered in the referenced issue on discordapp/discord-api-docs.

[bensaine]

@favna Ah ok! Didn't realize this was for getting a user's custom status. Looking over code now, looks good! Nice job :)

[DevYukine]

Stop spamming peoples notifications with this, if you want to use this just run the fork instead of original d.js in your bot.

[izexi]

A getter for Activity#createdAt (which simply returns new Date(this.createdTimestamp)) should be added for consistency

[kashima-dot-com]

gg

[JMTK]

Will this support multiple activities(array of activities as documented)? Right now the library only supports a 1 to 1.

[favna]

@JMTK That is not part of this pull request and falls out-of-scope. You can create your own pull request to cover such a feature if you want.

[RohitM-IN]

cant wait for this custom status update for bots. all checks passed dev ?

[favna]

@RootAndroid58 this will not allow bots to set custom status. Bots cannot have a custom status by API limitation. This will only allow bots to read the custom status of users.

And yes as you can clearly see all checks have passed. This PR is waiting for someone like @SpaceEEC to review it.