sqlite - use []byte for blobs

[javiercbk]

To keep the API consistent with mysql

case "blob", "binary", "varbinary", "tinyblob", "mediumblob", "longblob":
    return "[]byte"

and postgres

case "bytea", "blob", "pg_catalog.bytea":
    return "[]byte"

I suggest sqlc uses []byte instead of []uint8. If the field is nullable, it is pointles to have a *[]uint8 (or *[]byte) because slices are already pointers, and a slice can be nil