[ew] link and image modals inside of the block edit modal are full width and look odd

either need to avoid the nested dialogs, or handle that explicitly with styles to keep max width and positioning smaller than parent dialog

Reproduce the issue by opening the link and image modals from within the block edit modal, then inspect the modal styling and nesting behavior. The work is done when the nested dialogs no longer appear full width and have appropriate max width and positioning within the parent dialog, or when nested dialogs are avoided.

Written by the indexing model from the issue text.