UUID field type should be []byte not string

[willbuckner]

sqlboiler-crdb/driver/crdb.go

Lines 348 to 349 in d74f22d

	case "string", "collate", "bit", "interval", "bit varying", "character", "character varying", "inet", "uuid", "text":
	c.Type = "null.String"

I was surprised to see UUID columns represented as string in generated Go. The CockroachDB Manual clearly states that this data is stored as bytes, and in my Go code, I pass them around as []byte as string conversion is a completely unnecessary waste of resources.

I realize this would be a breaking change, but can we make it configurable? Thanks for looking into this.

[glerchundi]

@willbuckner I don't have time right now but I found it was already discussed here: aarondl/sqlboiler#58, maybe ask in the core library first and depending on the status and reasoning we'll proceed with this or not.