Update to JDA 6 and add support for new components

[freya022]

[yttrian]

Hi! I recently started rewriting my JDA 4 bot and was wondering if there's a timeframe for when JDA 6 support will be ready. Already really appreciating the work that went into this library, and the ergonomics it provides. Thanks!

[freya022]

You can use this PR as a snapshot with

repositories {
    mavenCentral()
    maven("https://jitpack.io")
}

dependencies {
    implementation("io.github.freya022:jda-ktx:e7b0e50683")
}

If you don't want to use snapshot builds (or Jitpack as a whole), as this PR is based on what I did for my own library, you can use it in the meantime, the module is independent but be aware that it is missing some stuff.