Made a working iframe base foreign key selector.

Requires more work, but it is a proof of concept that works.
Cleanup iframe base foreign key selector.
Styled the modelchoicefield iframe.
Made it possible to hide the menu for more focused views.
Made search work when selecting foreignkey.
objecttable: Keep querystring when paging.
Made create work with modelchoicefield.
Prefix the querystring args used for foreignkey selection.
Style submitrow for no menu.
Reset foreignkey iframe on show.
Added a body class that prevents scroll. Perfect for overlays.
Added loadspinner for floating iframe.
Cleanup iframe styles.
Prepare modelchoicefield for previews.
Prepare modelchoicefield for previews.
Made a working foreignkey preview pipeline.
Foreign key image selector is usable.