* Get PKcols inside tables - done with SQL for tables and
with an additional step in Haskell for views.
This fixes an fk column being considered as a pk column on views
and corrects the test added on
https://github.com/PostgREST/postgrest/pull/1875/files/1d549768580310e18aac4ffa6dbd01c5b77934a7#r853674126
* classify view key dependencies in SQL
* remove Column from Relationship
* Merge cols/fcols in Relationship and
ensure allM2ORels and allViewsKeyDependencies fk columns
are ordered - done by attnum in SQL
* Cardinality now contains relColumns instead of Relationship -
this simplifies getJoinConditions.
Just having the QualifiedIdentifier gets us closer to having
Relationship as a Table attribute since it avoids a cyclic dependency
* remove unnecessary findTable
* modify RootSpec test
steve-chavez