[ORCA] Support left/right outer join order hints

[dgkimura]

Commit https://github.com/greenplum-db/gpdb/commit/ef7eec414877eb274e8c4351a2ef425139174d56 added a framework to support inner join order hints.

This commit extends that framework to support left (LOJ) and right (ROJ) outer joins. LOJ and ROJ have the following additional restrictions:

1. Join predicates are non-transitive. For example:

   SELECT * FROM t1 LEFT JOIN t2 ON t1.a=42 LEFT JOIN t3 ON t1.a>4;

   Predicates a=42 and a>4 cannot be pushed below their respective join conditions. Otherwise NULL values may not be output correctly.

2. Join kind (e.g. left, right) is affected by the order. For example:

   SELECT * FROM t1 LEFT JOIN t2 ON t1.a=42;

   Leading((t1 t2)) requires a left join Leading((t2 t1)) requires a right join

CLogicalNAryJoin stores the necesary information to handle these restrictions inside CScalarNAryJoinPredList.

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Dev-pipeline: https://dev.ci.gpdb.pivotal.io/teams/main/pipelines/gpdb-dev-orca-join-hints-LOJ-rocky8