project: vm-arm-virt-[test]-inc.mk: create inc makefile for VMs

create a new platform which name starts with the `vm-` prefix,
complementing the legacy `generic` platform:
- `generic` is a platform for Trusty OS images running
   as TEE, requiring placeholder hals for emulating the
   hw dependencies or emulating provisioning lifecycle (system state server).
- `vm` is a platform for Trusty OS images running as virtual machines,
   requiring Trusted HALs (remote HWCrypto and Secure Storage
   services)

Bug: 394704863
Test: build any Trusty target
Change-Id: Ieb18d69fb8001f4b8862d90b9219ef4cb13e7e19