Merge 'IN queries' from Glauber Costa
Implement IN queries.
It is currently as todo!(), but my main motivation is that scavenging
for EXPLAINs, that pattern, at least in simple queries like SELECT ...
IN (1,2,3) uses the AddImm instruction we just added.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#2342