Add JJS chunked dropper

[terrorbyte]

Do not merge until the Go 1.23 mod changes as this relies on slices.Chunk.

Adds a JJS based chunked dropper. It generates a valid JJS script with a base64 (I tried to use java.util.HexFormat ones, but weirdly that is less supported) blob that will write to a file, and if execute is true it will change the file permission and execute the payload. The chunks are not the chunk max-size of the whole JJS payload but chunks of the payload, which may want to be adjusted for clarity.

Of note, this was needed for an OFBiz binary dropper version but our Go based payloads are ye olde 3-4Mb and the groovy max size required ~490 requests :sweat_smile: so there might be some more work on that in the future.