Support Kotlin/JS

[DRSchlaubi]

This PR attempts to provide Kotlin/JS support for Kord (see #69)

Breaking Changes

• The following member functions were replaced by extension functions. Importing the extension functions should fix this breaking change.
  • dev.kord.common.Locale.asJavaLocale -> import dev.kord.common.asJavaLocale
  • dev.kord.core.cache.KordCacheBuilder.lruCache -> import dev.kord.core.cache.lruCache
  • dev.kord.rest.builder.message.create.MessageCreateBuilder.addFile -> import dev.kord.rest.builder.message.create.addFile
  • dev.kord.rest.builder.message.modify.MessageModifyBuilder.addFile -> import dev.kord.rest.builder.message.modify.addFile
  • dev.kord.rest.request.RequestBuilder.file -> import dev.kord.rest.request.file
• The type of the following declarations was changed from java.util.Locale to dev.kord.common.Locale (if you really need to use the Java class, use the asJavaLocale extension):
  • dev.kord.core.entity.Guild.preferredLocale
  • dev.kord.rest.builder.guild.GuildModifyBuilder.preferredLocale
• All annotations in dev.kord.common.annotation and the dev.kord.gateway.PrivilegedIntent annotation now have BINARY instead of RUNTIME retention. This means they are no longer visible for reflection.
• All maven consumers must append -jvm to their artifact IDs for kord-common, kord-rest, kord-gateway and kord-core.
• The core-voice capability has been removed, please use the kord-core-voice artifact instead.

[lukellmann]

@DRSchlaubi we should update the PR description to include migration issues/steps (artifact changes, member to extension conversions), then it's good to go

[lukellmann]

about annotation retention, this is how kxser does it, should we do it like this too?

@MustBeDocumented
@Target(AnnotationTarget.PROPERTY, AnnotationTarget.CLASS, AnnotationTarget.TYPE)
//@Retention(AnnotationRetention.RUNTIME) // Runtime is the default retention, also see KT-41082
public annotation class Serializable(
    val with: KClass<out KSerializer<*>> = KSerializer::class // Default value indicates that auto-generated serializer is used
)

it would mean that it's still available at runtime on jvm at least, i.e. no breaking change

[DRSchlaubi]

IMO these annotations shouldn't have been on runtime to begin with

[lukellmann]

IMO these annotations shouldn't have been on runtime to begin with

but now they are, so why not keep it that way?

[lukellmann]

#659

[DRSchlaubi]

I don't really see the benefit of keeping it

[lukellmann]

alright, it's fine for me