Beefed up sqlcoverage testing of new 2-table join syntax.
Prohibit NLJ/IndexScan plans where index scan is distributed and based on inner-outer expression
Merge branch 'eng_3038_merge' into sqlcoverage-next

Conflicts:
	tests/scripts/examples/sql_coverage/basic-joins.sql
	tests/scripts/examples/sql_coverage/join-template.sql
Merge remote-tracking branch 'origin/eng_3038_merge' into sqlcoverage-next
pseudo-merge of eng_3038_merge
Merge branch 'ENG-3038-merge-join-code-paths' into sqlcoverage-next
ENG-3038 fix wrong answers in ad hoc / sqlcoverage, mistaking (OUTER JOIN) 'ON col=constant' for a valid SP qualifier