RFR: 8241080: Consolidate signature parsing code in serviceability tools

[Daniil Titov]

Please review a change[1] that centralizes the signature processing in serviceability tools to make it capable of being easily extensible in the future.

Testing: Mach5 tier1-tier3 tests successfully passed.

[1] http://cr.openjdk.java.net/~dtitov/8241080/webrev.01 
[2] https://bugs.openjdk.java.net/browse/JDK-8241080 

Thank you,
Daniil