Moved fake manager creation and initial configuration into the proxy generator (Part I)

This is the first part of PR #372 (we split it up into 2 PRs as mentioned there).

It solves #371 partially, namely that the default behavior is available inside the c'tor call. Therefore it also solves the bug #368 (see the `when_faking_a_class_which_calls_virtual_property_members_in_constructor` test case).
Ad 2: Indeed, I thought about just calling it `IInterceptionSinkProvider`. I decided to put the "Lazy" in front to emphasize the important "one-time initialization" property. But I would also be happy calling it `IInterceptionSinkProvider` and just have the one-time thing in the XML Doc.

Ad 3: I'd also prefer making this interface and `IInterceptionSink` internal, but as you said `IProxyGenerator` is the problem. As I see no real usage of a public `IProxyGenerator`, I planned to make another PR, which will make all three interfaces internal. This is one of the things I avoided to have less changes in this PR.