[PATCH i-g-t] tests/intel/kms_joiner: Add a new test to validate non-joiner mode

[B, Jeevan]

Hi Karthik, 

I have addressed couple of comments you had given me regarding sorting can mode selection. 
But for validation method apart from commit failure I was trying to find alternate methods but couldn't find any lead, I have couple of opens. 1. Is there any debugfs entry where we get to know joiner is enabled or not. 2. Is it possible to get pipe active status after modeset/commit. Based on this we can validate. 

Thanks 
Jeevan B