If returning field contains nested selections then mutation is performed in two steps
1. Mutation is performed with returning columns of any primary key and unique constraints
2. returning fields are queried on rows returned by selecting from table by filtering with column values returned in Step 1.
Since mutation takes two courses based on selecting relations in returning field, it is hard to maintain sequence of prepared arguments (PrepArg) generated while resolving returning field. So, we're using txtConverter instead of prepare to resolve mutation fields.
* improved nested insert execution logic
* integrate error path, improve executing 'withExp' and improve tests
* add more readable types in '/Resolve/Insert.hs'
* set conflict context just before executing WITH expression
* 1) Tests for creating permissions
2) Test for constraint_on with GraphQL insert on_conflict
* Run tests with access key and webhook
* Tests for GraphQL query with quoted columns
* Rewrite test-server.sh so that it can be run locally
* JWT based tests
* Tests with various postgres types
* For tests on select queries, run setup only once per class
* Tests for v1 count queries
* Skip teardown for tests that does not modify data
* Workaround for hpc 'parse error when reading .tix file'
* Move GeoJson tests to the new structure
* Basic tests for v1 queries
* Tests for column, table or operator not found error cases on GraphQL queries
* Skip test teardown for mutation tests which does not change database state, even when it returns 200.
Insert trigger function: If query affects no rows then return `null`
Insert trigger function is modified to have
`IF r IS NULL THEN RETURN null; ELSE RETURN r; END IF;` in return statement.
### Description
What component does this PR affect?
- [x] Server
### Related Issue
#494
### Solution and Design
Use `quote_ident()` SQL function over `constraint_name` in insert trigger function definition.
### Type
- [x] Bug fix (non-breaking change which fixes an issue)
