[Menu] Add prop to disable auto focus

[th317erd]

I keep a fork of material ui simply and only because material ui Menu forcefully updates the element focus. I would greatly appreciate the merging of this PR to allow disabling this "feature". Thank you!

[oliviertassinari]

@th317erd The concept sounds good to me. However, we need to find a different wording, it's conflicting with:
https://github.com/mui-org/material-ui/blob/91ecbbd79dca4a2432157e79e6f4f5e2c9f8dfc6/packages/material-ui/src/Modal/Modal.js#L336

[th317erd]

@oliviertassinari That is exactly why I chose that prop name. I originally had it as autoFocus: false, but I needed the same thing to happen in Popover, and naming it this way allows it to be passed the as the same name via other props. I believe we WANT to have this prop pass though, because the intent is clear for the Menu, Popover, and Modal: don't steal my focus. Thoughts?

[oliviertassinari]

@th317erd Let's say we can this pull request property disableAutoFocusSelectedItem. Then I see a use case for disableAutoFocusSelectedItem={true} and disableAutoFocus={false}. A developer might want to move the focus to the menu without focusing on the first item, this way, a user can use the keyword to focus an item without having an item focused by default.

[th317erd]

@oliviertassinari Good thought! You are correct. I just pushed a new commit that renames this property. Thank you for your thoughts on this. :)

[oliviertassinari]

@th317erd Thank you :)