New repo for System Fatal Error Diagnostics for POWER Systems

[zshelle]

The design proposal is here: 
https://gerrit.openbmc-project.xyz/#/c/openbmc/docs/+/18591/

In the design proposal, I indicated we need a repo for the analyzer side 
and the isolator side of the diagnostics. The analyzer side will all be 
OpenBMC specific code. That is the easy one. The isolator side will be 
common code used throughout several projects within OpenPOWER in 
addition to its application in OpenBMC. It's been pointed out to me that 
there will be some convenient advantages to putting this isolator repo 
in the OpenBMC project. However, it will be used heavily in several 
OpenPOWER projects. I should point out that while the isolator is 
currently geared towards POWER, it has the potential to be used on other 
architectures in the future. I would appreciate any input on this topic.