RFR (M) JDK-8237766: Enhance signature API to include ResolvingSignatureStream

[Lois Foltan]

Please review the following enhancement to introduce a 
ResolvingSignatureStream class into the signature API support.  This 
consolidates numerous places in the code that manually walk through the 
differing parts of a signature and request to resolve or find the 
respective underlying types.  ResolvingSignatureStream now provides this 
capability in order to eliminate the code duplication and redundancy.

open webrev at: http://cr.openjdk.java.net/~lfoltan/bug_jdk8237766.0/webrev/
bug link: https://bugs.openjdk.java.net/browse/JDK-8237766
contributed-by: Lois Foltan, John Rose

Testing: hs-tier1-3 (all platforms), hs-tier4-6 (linux only)

Thanks,
Lois