Buffer JSON encoding/decoding

[Hexcede]

Lune can't currently encode/decode buffers that have been JSON encoded by Roblox (such as when written to DataStores)

My particular use case is interacting with DataStores via OpenCloud within Lune, specifically, reading a key that contains a buffer, and then decoding that encoded buffer into a buffer datatype inside of Lune.

#202 and #203 are also relevant