Enable ARM testing for CI/CD

[bchalios]

Problem

At the moment, our CI/CD workflows run only on x86. We need to extend this for ARM/ARM64 platforms. This will allow us to test our plugins for devices such as Coral, etc. and produce binaries for these architectures automatically.

Requirements

1. We need a vaccel-deps container image for building vAccelRT
2. We need rootfs for ARM
3. We need Linux kernel for ARM

Sub-module issues

• [x] vaccelrt: https://github.com/cloudkernels/vaccelrt/issues/19
• [x] Firecracker: https://github.com/cloudkernels/firecracker/issues/8
• [x] virtio-accel: https://github.com/cloudkernels/virtio-accel/issues/9