adopt connector best practices for FB Marketing source

[sherifnada]

Tell us about the problem you're trying to solve

We'd like to follow the published connector development best practices on this connector.

Checklist

• Check connection verifies permissions upfront
• Check connection failure emits actionable error messages. This will probably require you to think about the failure modes that can occur (e.g: timeout, permission not granted, token does not exist, etc.. -- make sure that you add custom integration tests to verify each of these failure modes, or unit tests if you can mock the HTTP requests involved)
• If API connector: integration tests validate that every stream outputs data (you may need to seed the underlying API with fake data). This will establish a baseline confidence that the connector works correctly on every data stream. If this is not possible, please reach out to @sherifnada with the reason to discuss how to move forward.
• If API connector: backs off on hitting rate limits (instead of just failing/exiting)
• If API connector: implements incremental sync (where possible -- not all streams will allow this)

[eugene-kulak]

The estimation:

• Check connection verifies permissions upfront - 30m
• Check connection failure emits actionable error messages. - 1h
• Check if integration tests can be run for every stream - 1h
• If API connector: backs off on hitting rate limits (instead of just failing/exiting) - 30m

Dev Total: 2h

[sherifnada]

Thanks @eugene-kulak this looks great. Let's make sure we implement it in the right facebook connector 😜

[sherifnada]

(the new connector introduced in #1552

[eugene-kulak]

#1699 overlapped with this ticket and has all job done there