Added new API to SBStructuredData class

Summary:
 - Added API to access data types
    -- integer, double, array, string, boolean and dictionary data types
    -- Earlier user had to parse through the string output to get these
       values

 - Added Test cases for API testing

 - Added new StructuredDataType enum in public include file
   -- Replaced locally-defined enum in StructuredData.h with this new
      one       
   -- Modified other internal files using this locally-defined enum

Signed-off-by: Abhishek Aggarwal <abhishek.a.aggarwal@intel.com>

Reviewers: clayborg, lldb-commits

Reviewed By: clayborg

Subscribers: labath

Differential Revision: https://reviews.llvm.org/D33434

llvm-svn: 304138