Add CurrentValues.SetValuesExcept()

[urza]

In my asp.net core + ef core I am using this update mechanism a lot:
_context.Entry(existing).CurrentValues.SetValues(received);

Many times I want to update only some properties of the object.
There are several ways how this can be accomplished.. creating and sending ViewModel, setting the properties manually instead of using the CurrentValues.SetValues or overriding the values of some properties manually.
These all works, but they add some complexity.
I would love to have something like:

SetValuesExcept("PropertyX", "PropertyY")

that would update all properties on my object except PropertyX and PropertyY.

[ajcvickers]

Note from triage: having some form of exclusion list could be useful here. We will need to discuss design and API.