The failing test from the previous commit causes the following metadata
to be emitted:

    .property instance class [mscorlib]System.Action`1<bool> Property()
    {
        .get instance class [mscorlib]System.Action`1<bool>
                         Castle.Proxies.IDerivedProxy::get_Property()
    }

    .property instance class [mscorlib]System.Action Property()
    {
        .get instance class [mscorlib]System.Action
                         Castle.Proxies.IDerivedProxy::get_Property()
    }

Obviously we need to switch to explicit implementation for one of these
events in order to avoid a name collision. We do that by changing the
"collision detection" such that it does not take into account events'
return types; only their name matters.

Since events and properties have very similar metadata, the same issue
we just solved for events might be present for properties; let's test
this suspicion.

This might be a PEVerify bug.

Given that the C# compiler would force us to implement either the base
or derived property explicitly (in a class implementing `IDerived`),
let's do the same in DynamicProxy. Use the same approach as for events.