Support config location from compatible system interface

Update reading the `Names` property from the
`xyz.openbmc_project.Configuration.IBMCompatibleSystem` interface that
contains a list of compatible subdirectories in priority order to find
the location of the configuration file to use. The first configuration
file found from checking these subdirectories is used. The order in
which configuration files are looked for remain unchanged and are:

1.) Override location: /etc/phosphor-fan-presence/[app]
2.) First config file found under one of these subdirectories
    i.e.) `Names` = "rainier-2u" "rainier"
        1.) /usr/share/phosphor-fan-presence/[app]/rainier-2u
        2.) /usr/share/phosphor-fan-presence/[app]/rainier
3.) Default location: /usr/share/phosphor-fan-presence/[app]

Tested:
    Verified location order above loads the expected config file

Change-Id: If6eb36e1a808544da0795db609658eb57db112c0
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
2 files changed