phosphor-debug-collector: Add DumpPrefix property to faultlog dump entry Add support for the optional DumpPrefix parameter in FaultLog CreateDump requests. Parse and validate DumpPrefix in Manager::getAndCheckCreateDumpParams(), throwing InvalidArgument if the parameter is not a string, and pass it to faultlog::Entry to populate the D-Bus DumpPrefix property. Google-Bug-Id: 559785933 Tested: https://paste.googleplex.com/6159609547587584 Fusion-Link: https://fusion2.corp.google.com/482dee38-f2d0-3405-b3ce-e2f7628384e7 (platform15) Fusion-Link: https://fusion2.corp.google.com/366ab6bc-d078-3333-8edb-ff3a0aa4b346 (platform18) Fusion-Link: https://fusion2.corp.google.com/93913499-bb38-35d6-876d-8ad1e295cc9f (platform17) Fusion-Link: https://fusion2.corp.google.com/56afda78-0594-3ef9-af9b-dfca3911dc56 (platform11) Fusion-Link: https://fusion2.corp.google.com/ec6640aa-0a02-3891-b926-93d68e110f02 (platform11-emr) Change-Id: I9d55c3934c9f60b3be01686aa9413bfe9684249e Signed-off-by: Jasmine Cha <chajasmine@google.com>