Added OpenStack VM deployment job

• Add deploy_user_defined_vm job for configurable VM provisioning
• Implement dynamic OpenStack CLI command construction supporting:
  • Image selection by name/UUID via $VM_IMAGE
  • Flavor specification with $VM_FLAVOR
  • Security group array input ($VM_SECURITY_GROUPS)
  • Network/port options (
    VM_NETWORK/
    VM_PORT)
  • Floating IP association ($VM_FLOATING_IPS)
• Require core variables: VM_IMAGE, VM_FLAVOR, VM_SECURITY_GROUPS, VM_INSTANCE_NAME
• Add pipeline rule trigger via $DEPLOY_VM == "true"

assigned to @krish94

mentioned in issue #234