Add support for RIGHT OUTER JOIN

Tracks MB-33251

Right outer joins are shown as permitted by the syntax diagrams in the AsterixDB documentation. However there is no discussion in the AsterixDB documentation and there are no examples to illustrate them. May be better to address this issue in AsterixDB.

However, note that we also need to update the 6_n1ql and 7_using_index pages on the CBAS side.