* 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
Clarify the difference between arguments and parameters.
Parameters are part of the function definition, arguments are the values
passed to the function.
Also clarify the findProc function comments and error message.
* Add 300 response for overloaded functions with same argument names but different types
* Add Path type to handle validations and errors before defining the Target
Now that PgVersion is not part of DbStructure, Config is a more apt
module for it.
Also rename getDbStructure to queryDbStructure. AppState also had a
getDbStructure function for a record field.
steve-chavez