Add support for entity framework context extensions

[danielmarbach]

Describe the feature.

Raising this here because it is closest to where it might belong, but that doesn't necessarily mean it has to be implemented in this repository.

Is your feature related to a problem? Please describe.

There is non-trivial amount of code that is required to hook up entity framework contexts with the synchronized storage session. Ideally, this would not be something our customers would have to do and we would provide a convenience method on top of ServiceCollection similar to the AddDbContext extension method, encapsulating all the heavily lifting and corner cases.

See also #1500 and https://docs.particular.net/samples/entity-framework-core/#code-walk-through-unit-of-work-creating-data-context

Describe the requested feature

See above

Describe alternatives you've considered

The alternative is to have an extension method that can be copy pasted in a clearly visible spot somewhere.

Additional Context

No response