Can specify Times a verifiable expectation must be met

[IFYates]

Defaults to AtLeastOnce to match current functionality.

We had an issue testing a method modified properties within a reference type shared to a dependency. The current "Verify" checks can only compare against the current reference type state (see new CannotPostVerifyCallsByExpressionForModifiedReferenceTypeArgument fact).
The approach that we came up with was to support the "Times" concept directly in the "Verifiable" setup.

Given that the change is non-breaking by default and pretty clean, I thought it worth pushing back.

Full example in CanPreVerifyExactCallsByExpressionForModifiedReferenceTypeArgument fact, but in short:

mock.Setup(m => m.Method()).Verifiable(Times.Once()); // Require method to be called only once
// act
mock.Verify(); // Verify invocations match expected

[stakx]

This will probably have to wait a while until we have an answer in #373. Thanks for being patient! :)

[stakx]

This looks very promising to me, thanks for sharing this!

One aspect that might benefit from some more discussion is whether .Verifiable is the best place for specifying a Times. It's not unreasonable; I'm just wondering if it's generally obvious / discoverable / intuitive enough. I'd be interested to hear your thoughts on whether you've considered (a) adding Times as an additional parameter on the various .Setup methods; or (b) adding named methods to IOccurrence and then de-obsolesce that interface; or (c) any other options I'm not thinking of right now. :) (I'd say let's discuss that bit over in #373.)

I'd like to request one simple change:

• Could you please rebase this one commit on top of the develop branch of Moq's repo? The "merge develop" commits shouldn't end up in the develop branch. :)

I'd generally be OK with accepting this feature, but would prefer to leave the final decision up to @kzu whether anything like this gets merged at all, as mentioned in #373.