This commit introduces 2 new features into DevTools.
Directive level dependency inspection: Users can now view which dependencies their directives have injected in the property viewer tab. This view displays not only the dependency but also the resolution path that was used to service the injection.
Injector graph inspection: Users can now view a visualization of the element and environment hierarchies in their application. These trees are displayed separately but on the same page in the Injector Tree tab. User can click on individual injectors to view a list of all the providers configured in that injector, as well as highlight the resolution path from that injector to the root (with the corresponding environment injector connection highlighted as well).
PR Close#51719
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
