PP-741: Need a default job specific to Cray in PTL

Interface:Job()
Visibility: Public
Change Control: Stable
Synopsis: Modifications to assign value to 'vntype' attribute of a job, when platform is Cray.
Details:

• If platform is an actual Cray cluster or Cray ALPS simulator:
  • If 'vntype' is not defined then perform below:
    • Assign value to 'Resource_List.vntype' of job attrs as 'cray_compute'.

Interface: Server.submit()
Visibility: Public
Change Control: Stable
Synopsis: Modifications to consider aprun command if the platform is Cray.
Details:

• If platform is an actual Cray cluster or Cray ALPS simulator:
  • If obj.create_script is not defined and vntype is equal to 'cray_compute' then perform below:
    • Construct default aprun command as "aprun -B"
    • If script is defined then append it to default aprun command else append default job executable as '/bin/sleep 100'.