Array Toggle Field and Object Validation hooks

[larsmaxwell]

This is an expansion of the core array field work in #238

• Create a component called ArrayFieldToggle which wraps the array field. This component is responsible for showing and hiding entries in an array field. The markup and functionality for this would be passed through to the array field as the FieldArrayTemplate parameter

• Add basic object validation hook for the array field. Which item in an object is required in order for the user to add more items to the Array field?

• Create tests that test the toggle functionality, as well as the basic object key value validation.

• Update the demo form on staging to use the new version of the array field.