Fix minor FormApi bugs and add initial form API tests

[crutchcorn]

This PR:

• Fixes formApi.update to behave as I would expect it to
• Fixes typings for pushFieldValue and insertFieldValue helpers
• Prevents throwing an error on swapFieldValues
• Adds initial tests for form API
• Fixes formApi.reset to include form values

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Additional details and impacted files

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  Misses          ?       48           
  Partials        ?        6           

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