rql #71415 needs to allow outer join on rhs of final relation and in HAVING expression [validation pending]

to express queries where we want an outer join on attribute values

prioritynormal
typeenhancement
done in0.29.1
load0.500
load left0.000
closed by#6afe7acaf314 allow optional on final relation (rhs only) and in having expression (hence Comparison node gain a 'optional' attribute). Closes #71415