start_debugvtty_session: function to create debug vtty session
start_debugvtty_session: function to create debug vtty session

Added a function to start a virtual tty debug session for the given timeout,
paritionid and sessionid, this will help in tests which requires to run phyp
commands

Signed-off-by: Abdul Haleem <d72979407b2438b90c42979d11f88d04d190c5d3@linux.vnet.ibm.com>

open-power/op-test-framework,open-power/op-test-framework,open-power/op-test-framework