The menus weren't using the `mat-menu` component correctly which had led to some inconsistent spacing and the need for style overrides. These changes correctly wrap the menu content in `mat-menu-item` which has the added benefit of having keyboard support. I had to keep some of the overrides in order to preserve the dense layout of the menus.
I've also cleaned up the component by:
* Removing some unnecessary styles.
* Switching single-class usages of `ngClass` to `class.` bindings.
* Not using `br` tags for spacing.
PR Close#45665
