Hothd: Add active payload version to Software Version DBus.

Export the active payload version on the xyz.openbmc_project.Software.Version D-Bus interface (/xyz/openbmc_project/software/hoth_payload) when the PayloadStatus host command is supported by the EC.

Tested: Unit test in gbmc-testing docker container. https://paste.googleplex.com/6502620138176512
Google-Bug-Id: 533559992
TAG=agy
CONV=151513a5-c852-4e60-a901-6d9077c4b186

Change-Id: I42129810a43e1dc190a1a453e3d60bb907ee2e93
7 files changed