cryptui: Add a partial implementation of CryptUIWizImport.

[Juan Lang]

> It persists in Windows, yes. Haven't tested Wine, where do you see a crash?

In crypt32.  I wrote a quick test program that does what your patch
does, and it crashes adding the certificate to the root store.  I'll
send a patch shortly that'll avoid the crash.  Nevertheless, this
won't do what you want in Wine:  the root store is read-only in Wine.
--Juan