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).
I had trouble parsing this name. Perhaps
`Should_ensure_interception_sink_is_initialized_but_not_fetched_when_no_method_on_fake_is_calls`

Hmm. Not great. But does get the fact that we're denying "fetch"ing.
Slightly less awkward if we split into two tests? One for ensuring initialization and one for not fetching?