More control of the Preview to bring it up to par with other modals

[LorenzoSapora]

• Clicking outside of the preview doesn't close the preview (common behaviour in accessible modals)
• When extending resources (UsersModified extends User extends Resource extends NovaResource), the preview defaults to the resource uriKey/id. Some control of this would be great.
• Like the action modal, some control over the text, and/or additional buttons would be nice
• Modal size doesn't work on preview modals