Add platform field to ActivityData and DiscordActivity

[giginet]

Summary

This PR adds platform property to Activity.

When users play games from consoles. The Discord Activity API returns the below response.

{
  "type": 0,
  "timestamps": {
    "start": 1702191977428
  },
  "platform": "ps5",
  "name": "Sonic Superstars",
  "id": "20ac8563beebf2ec",
  "flags": 0,
  "created_at": 1702191977427,
  "assets": {
    "small_image": "mp:external/at5adOeXGcCj4jN9_zB0SiIL3FR8wOxq_d39CDh9Pqo/https/cdn.discordapp.com/assets/playstation-logo-rich-presence.png"
  }
}

According to the documentation, this field is undocumented, but I confirmed this value was returned.

See also the this PR for Discord.py.

[DRSchlaubi]

Are these documented, if so could we use a "kordenum"

[giginet]

Do you mean it should be an enum type to represent each playform?

[DRSchlaubi]

Something like this: https://github.com/kordlib/kord/blob/main/common/src/commonMain/kotlin/entity/DiscordMessage.kt#L1-L38

[giginet]

I found an implementation like this.
https://github.com/kyranet/discord-api-types/blob/0aa384ca9a8fe5a35cc4d13f3e2c0b4e5a55c0ca/deno/payloads/v10/gateway.ts#L229

But these platforms are inaccurate, so it's safer to be just a string.

[DRSchlaubi]

I found an implementation like this. https://github.com/kyranet/discord-api-types/blob/0aa384ca9a8fe5a35cc4d13f3e2c0b4e5a55c0ca/deno/payloads/v10/gateway.ts#L229

But these platforms are inaccurate, so it's safer to be just a string.

Kord enums do have an Unknown type which will be used in the case of an invalid type, however I can't find these type to the be documented anywhere

[giginet]

OK, I’ll define the enum values based on this.

[giginet]

@DRSchlaubi I defined the known platforms as the Kord Enum.

And I confirmed it works for a known platform or an unknown value.

[lukellmann]

thanks!