Allow using a query and cursor together when calling client.feed()

[ecooper]

This PR enables supplying a cursor value when using an unevaluated query with client.feed().

Description

This PR removes a check that prevented you from calling client.feed() with a query and a cursor. It is an unnecessary constraint, and event feeds will behave as you'd expect without this check.

Motivation and context

This change allows you to resume at a given cursor while still passing in a query to generate the event source. Before this change, you'd need to first evaluate the query for the event source yourself before calling feed with cursor.

How was the change tested?

• An integration test on client was added
• Existing integration tests pass

Change types

• • Bug fix (non-breaking change that fixes an issue)
• • New feature (non-breaking change that adds functionality)
• • Breaking change (backwards-incompatible fix or feature)

Checklist:

• • My code follows the code style of this project.
• • My change requires a change to Fauna documentation.
• • My change requires a change to the README, and I have updated it accordingly.

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[ptpaterson]

I think this is a good thing to do. The new test covers the use case well.

[jrodewig]

👍 I'll update the README in a separate PR. Thanks!