cryptui: Add a partial implementation of CryptUIWizImport.

[Juan Lang]

> Like I said, it's exactly the set of conditions that happens to satisfy
> Outlook. The typical scenario is that you can't connect to a secure
> server because of an invalid certificate and then forcibly import the
> certificate. The invalid certificates I tried on Windows where added
> to the root store.

But you don't check whether those conditions are true, and you march
ahead and install the certificate into the root store whether or not
they are true.  I'm sorry, but the code is just not correct.  Please
write some test cases.
--Juan