fix interface and path patterns to match D-Bus specification
fix interface and path patterns to match D-Bus specification

The old regex checks did not account for all the requirements,
namely empty paths and two-part names.

Tested: This rejects poorly-named interfaces and paths as expected.
        Tested interfaces:
        ""
        "xyz.openbmc_project.some-interface"
        "xyz.openbmc_project.some/interface"
        "bob"
        Tested paths:
        ""
        "/xyz/openbmc_project/some-interface"
        "/xyz/openbmc_project/some.interface"
        "xyz/openbmc_project/some/interface"
        "bob"

Change-Id: I3d8979c9eb19680c66a5031efd334a574f8f7be3
Signed-off-by: Vernon Mauery <4fbc0e9805d36da7c621cd4d73f3eb0d5b12b5f3@linux.intel.com>

openbmc/sdbusplus,openbmc/sdbusplus,openbmc/sdbusplus,openbmc/sdbusplus