Add kotlin DSL for list options

Currently, there is no kotlin DSL for list options.

Here is a very quick implementation I made of that (in my implementation I had to use reflection to grab the groupKey, but that's only bc I don't have access to your private api)

// OptionRegistrar (API.kt)
interface OptionRegistrar {
    fun <T> registerList(id: String, @BuilderInference block: ListOptionDsl<T>.() -> Unit): ListOption<T>

    fun <T> registeringList(id: String? = null, @BuilderInference block: ListOptionDsl<T>.() -> Unit): RegisterableActionDelegateProvider<ListOptionDsl<T>, ListOption<T>>
}

// API.kt
interface ListOptionDsl<T> : ListOption.Builder<T>, Buildable<ListOption<T>> {
    val optionKey: String
    val optionId: String
    val thisOption: CompletableFuture<ListOption<T>>

    fun OptionDescription.Builder.addDefaultText(lines: Int? = null) = addDefaultText("$optionKey.description", lines)
}

// OptionRegistrarImpl (Impl.kt)
class OptionRegistratImpl {
    override fun <T> registerList(id: String, @BuilderInference block: ListOptionDsl<T>.() -> Unit) = register(id, ListOptionDslImpl<T>(id, groupKey).apply(block).build())

    override fun <T> registeringList(id: String? = null, @BuilderInference block: ListOptionDsl<T>.() -> Unit) = RegisterableActionDelegateProvider(this::registerList, block, id)
}

// Impl.kt
class ListOptionDslImpl<T>(
    override val optionId: String,
    groupKey: String,
    private val builder: ListOption.Builder<T> = ListOption.createBuilder(),
) : ListOptionDsl<T>, ListOption.Builder<T> by builder {
    override val optionKey = "$groupKey.option.$optionId"

    override val thisOption = CompletableFuture<ListOption<T>>()
    override val built = thisOption

    init {
        builder.name(Text.translatable(optionKey))
    }

    override fun OptionDescription.Builder.addDefaultText(lines: Int?) = addDefaultText(prefix = "$optionKey.description", lines = lines)

    override fun build(): ListOption<T> = builder.build().also { thisOption.complete(it) }
}

// Extensions.kt
fun <T : Any> ListOption.Builder<T>.binding(property: KMutableProperty0<List<T>>, default: List<T>) {
    binding(default, { property.get() }, { property.set(it) })
}

Start by locating the OptionRegistrar declarations in API.kt, their implementation in Impl.kt, and the builder extensions in Extensions.kt. Compare the proposed list-option DSL with the existing option builder APIs, then verify that list options can be registered, built, and bound through the new DSL; the issue does not name a test file.