Add a --vm-type argument to the tests command in dev_cli.sh to
allow specifying the type of VM (regular or confidential). The
value is passed to the container via the VM_TYPE environment
variable.
Also extract a prepare_igvm_files() helper function to reduce
duplication when copying IGVM files for confidential VM tests,
and call it from both integration_cvm and metrics paths.
Signed-off-by: Muminul Islam <muislam@microsoft.com>
9f64400943