TH simplification for Luxi

This patch simplifies the generation of save constructors for LuxiOp
by always using showJSON over an array of JSValues, instead of having
to pass showJSON in most cases, except the 5-tuple case.

Signed-off-by: Agata Murawska <agatamurawska@google.com>
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
[iustin@google.com: fixed a few issues]