dev: Prime the FormsLoader when querying form connections

[justlevine]

What

This PR primes the FormsLoader when using the FormsConnectionResolver.

Why

Since GF only allows you to query for the entire form, theres no difference between Connection Resolver query and the actual model population. By priming the dataloader cache, we can prevent the unnecessary extra database queries.

How

Testing Instructions

Additional Info

Checklist:

• This PR is tested to the best of my abilities.
• This PR follows the WordPress Coding Standards.
• This PR has proper inline documentation.
• This PR has unit tests to verify the code works as intended.
• The changes in this PR have been noted in CHANGELOG.md

[codeclimate]

Code Climate has analyzed commit 298ecf6 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 84.4% (0.0% change).

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