OAuth flow: Refer to AuthSpecification config to format outputs with correct oauth response structure

[avida]

For now we have hardcoded object strucutre for each oAuth backend. E.g. for Asana response should be {"credentials": "refresh_token": ".."}, for trello or facebook its plain object {"key": "value", "key2": "value2"}, for some connectors it should be {"authorize": {"key": "value"}} etc.

We need to come up with generic solution to read response structure from connector's spec and not rely on hardcoded structure.
Output object path should consist of first rootObject value and oauthFlowOutputParameters path (except last one which is field name).