New topic: Getting the DbContext outside of a Controller

- [ ] Getting the DbContext outside of a Controller
- [ ] Accessing scoped services outside of an HTTP request.

per @davidfowl
There's enough confusion here that I think we should have a first class topic for it on the EF docs:

https://www.reddit.com/r/dotnet/comments/7cednh/how_to_grab_a_dbcontext_from_outside_a_controller/
We should probably also have something on accessing scoped services outside of an http request.

Can one of @ajcvickers or @divega provide the sample for *Getting the DbContext outside of a Controller*?

@rynowak @danroth27 who's the contact for _Accessing scoped services outside of an HTTP request?_