fix(dataconnect): Refactor CRUD helpers to use GraphQL variables and @allow directive (#3182)

* add tests checking for new GQL output for [insert,upsert](many)

* change mutation functions to use @allow

* factor out common code after @allow changes

* update tests to expect @allow

* update the @allow directive for list inputs

* initial fix

* address reviewer comments

* fix style and normalize expected + actual query strings in tests

* add fdc to integration test documentation and update integration test artifact ignores

* improve getTableNames variable naming for clarity

* add 10k limit and nested coalesced field keys for @allow

* de-duplicate code in mutaiton CRUD functions, and refactor tests

* update contributing

* add maxCount to array bulk insert variables

* limit @allow nesting to _on_ relational fields

* update tests

* address reviewer comments