Add extension methods/properties to Kotlin types for creating Nbt versions of a type.

[Ayfri]

Some utility methods/properties could be added on kotlin classes to simplify creation of Nbt types. I actually have some methods listed in the examples on some projects and I use them often.

Exemples :

• "test".nbt to transform a String to a NbtString.
• true.asNbtByte() to transform a Boolean to a NbtByte.
• listOf(1, 2, 3).asNbtList() to transform a List of Number to the NbtList version, maybe to the Nbt[Number]Array version when possible.