Adjusting CSS to better allow for added field settings by custom code.

[kimcoleman]

…; adjusting JS to toggle all file fields properly

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• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

This PR moves a few field settings around + improves the markup CSS so that it is easier to:

• Target field settings with JS
• Jump fields around
• Add new fields with a future hook.

There is also some JS improvement to hide the "Required at Checkout" individual field setting based on the group setting.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?