[DEV] Add Mountain Node support

[evanmcc]

Short Description
Since https://github.com/Cray-HPE/hms-scsd/ is unlikely to become an OpenCHAMI component, we need to work around the fact that Mountain (aka CertSSH) nodes require it to be functional. This will require ripping out all of the code that creates and fetches these certs, and replaces them with a call to get the bmc's password, writing a different config line using that passwords, and writing a new expect script that allows us to connect to the correct node on the BMC.

Definition of Done
Mountain nodes found in SMD can be connected to via conman.

Additional context
I don't love having all the passwords in the config file, and I don't want to make the problem worse, but this is the simplest "for now" solution, which should get us to the point we can deploy this on some bigger systems and do some scale tests while we design and develop a better system.