[Mat-Menu] Feature Request : add ability to remove backdrop

[seedy]

Bug, feature request, or proposal:

Just like dialogs, menus should be more configurable regarding their behaviour.
It's right now possible to stop menus from overlapping their trigger, but still the behaviour is not following material guidelines.
Removing backdrops might be a solution.

What is the expected behavior?

1. Click on trigger button should open menu (with or without overlapping it)
2. (If visible) Hover over trigger button with menu open should have the same behaviour as with menu closed
3. Dismiss a menu by tapping outside of the menu, or by tapping the emitting button (if visible). (https://material.io/guidelines/components/menus.html#menus-behavior)

What is the current behavior?

Backdrops are disabling the whole behaviour regarding emitting buttons

What are the steps to reproduce?

https://stackblitz.com/edit/angular-bcfxwg

What is the use-case or motivation for changing an existing behavior?

Help us follow the guidelines bro!

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Is there anything else we should know?

[bankin]

Is there expected release date for this?

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}