kunit_tool: update to support kunit_watcher

Return objects when building config, building kernel, and parsing
test log in order to provide full context of kunit run.

Change-Id: If410ac7e2b747c80c952fd2a9983bb2f4577fd33
Google-Bug-Id: 116626752
Signed-off-by: Avi Kondareddy <avikr@google.com>
5 files changed