Adopt connector best practices for shopify 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.

Since this connector is Singer based, for each of the below items please verify whether:

• the singer tap already implements it
• the singer tap does not implement it and would require forking the tap to implement
• it's something we can implement easily on top of the Singer tap without forking it

If implementing any of the below items would require forking the Singer tap, please notify @sherifnada and move on to the next issue.

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)

[yevhenii-ldv]

The estimate time to complete this task is 8 hours.

Checklist

• Check connection verifies permissions upfront - 1h
• Check connection failure emits actionable error messages. - 30m
• If API connector: integration tests validate that every stream outputs data (you may need to seed the underlying API with fake data). - 4h to fill the account with fake data for all streams using API and test every stream.
• If API connector: backs off on hitting rate limits (instead of just failing/exiting) - 30m on testing
• If API connector: implements incremental sync (where possible -- not all streams will allow this) - 2h