Schema: Only allow user to scroll central container in edit field and add field modal

[zcolah]

Describe the bug
Currently when a user opens the modal to add a field or edit a field, they can scroll the entire container.

Solution
This should not be the case. The header of the modal should be pinned to the top of the modal and the footer should be pinned to the bottom with the central area only scrollable.

Please see Loom video to understand problem and desired solution.
https://www.loom.com/share/e8f72083cb6747298a5fca73ecce8104

[agalin920]

@theofficialnar DialogContent component typically auto overflows and does not affect DialogTitle nor DialogActions. Might not be implemented properly