Accelerate DynamicProxy test execution

[stakx]

Test execution has got much slower ever since I introduced a large number of test cases in ParameterDefaultValuesTestCase. The situation can easily be improved, since the slow-down is largely due to a higher number of peverify.exe invocations. Most of these aren't actually necessary, since it is the same proxy type getting generated for each test case.

We could either split the test fixture in two – with only one deriving from BasePEVerifyTestCase and getting the tests where PEVerify should be run – or we could come up with a way to skip peverify.exe for single tests. For now, I am opting for the latter solution.

I am aware that this is something of a quick fix. In the long run, it would probably make more sense to review all tests and decide which really need to be in a BasePEVerifyTestCase-derived fixture, and which ones don't really require any IL verification. Such a review will take much more time, I'm holding that off for the moment.

[stakx]

Interestingly, while these changes drastically reduce test execution time on my local machine (by nearly 1½ minutes), they hardly appear to affect our CI builds at all. So perhaps there's not much point going ahead with this, better to wait for the bigger "to BasePEVerifyTestCase or not to BasePEVerifyTestCase" review? I'll sleep on it.