Replace all 'render' props to 'children' props in Formik elements

[ftianli-amzn]

Issue #, if available:

With the Formik v2.x upgrade (#236), there is a new deprecation warning shows in the browser console (for screenshot see the PR above).

The solution is to replace all the usage of render props to children props in <Field>, <FastField>, <Formik>,<FieldArray> elements, according to the official guide: https://formik.org/docs/migrating-v2#deprecation-warnings

Description of changes:

• Replace all 'render' props to 'children' props in Formik <Formik> <Field> <FieldArray> elements
• Update jest snapshot files

Note:

1. The children props can be used implicitly without stating children= (https://reactjs.org/docs/render-props.html#using-props-other-than-render)

2. In Enzyme's mount() method, children props can't be put directly inside the element, so I state children= explicitly in the specific unit tests.
   

Testing:

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