[OpenBMC] Support setting root user password for the BMC

[whowutwut]

This is not yet available in the BMC, but we can get started on adding in the support in xCAT:

The man page for rspconfig show existing function:

       rspconfig noderange admin_passwd={currentpasswd,newpasswd}

       rspconfig noderange general_passwd={currentpasswd,newpasswd}

       rspconfig noderange *_passwd={currentpasswd,newpasswd}

I think we would want to follow this, but the only thing that would be supported is admin_passwd

The password interface is here: Password.interface.yaml

I got the following information from OpenBMC team about the API:

Method: POST
Endpoint: /xyz/openbmc_project/user/root/action/SetPassword
Data: { "data": ["passw0rd"]}

This should be enough to get some code going that would just return 503 until the service is in the code.

[xuweibj]

https://github.com/xcat2/xcat-core/wiki/rspconfig-password

[gurevichmark]

Do we want this command to also modify xCAT passwd table to store the new new pw there ?

[gurevichmark]

man page for rspconfig command should also be updated to include pw changing options under OpenBMC section.