Admin: Fix height of controls in `extra_tablenav`.

Add CSS & update selectors so that controls added in the `extra_tablenav` region of list tables inherit the compact sizing used by core table nav controls.

Reviewed by johnbillion.
Props johnbillion, hbhalodia, mukesh27, sabernhardt, abdullah17, r1k0, joedolson, nilambar, shailu25.
Fixes #64796.

git-svn-id: https://develop.svn.wordpress.org/trunk@62115 602fd350-edb4-49c9-b593-d223f7449a82