New lint: Suggest usage of `mem::take`

[krishna-veerareddy]

mem::take is being stabilized in v1.40 so I was wondering if we should add a lint to detect occurences of mem::replace(&mut T, T::default()) and suggest usage of mem::take(&mut T) instead.

Let me know if this is something that's useful and I can start working on it.

[Shnatsel]

I believe #4485 could benefit from this

[krishna-veerareddy]

Fixed in #4881. Closing.