The changes here:
1. Make it easier to discover where nsIPKCS11 is implemented / make it easier to
discover what the file implements.
2. Reduce global scope pollution.
3. Make nsCrypto.h no longer unnecessarily exported.
4. Remove NS_CRYPTO_CONTRACTID from nsDOMCID.h, since the define isn't used
anywhere.
5. Move the definition of NS_PKCS11_CONTRACTID from nsDOMCID.h into PSM code,
since this contract ID is firmly in PSM territory now.
MozReview-Commit-ID: 2PdFM0mlL4R