Improvement suggestions for CBMC output

[peterschrammel]

• Runtime decision procedure -> Decision procedure runtime
• Measure duration for different phases separately: symex, conversion, solving
• goto checker iterations should be JSON/XML formatted
• fix incomplete plain text tests output in c_test_input_generator for multiple i/o values Add cover goals verifier [blocks: 3969] #3968 (comment)
• reconsider removing special cases when traces are output or not in JSON/XML vs plain text