[CLASS][QEMU][ADD] add wic support for qemu

Add class clea-os-qemu.bbclass, which allows building and running the Clea OS wic image with qemuarm, qemuarm64, qemux86, qemux86-64.

To run QEMU from the bitbake environment, run:

runqemu slirp nographic

To run it from a local environment, copy the contents of DEPLOY_DIR_IMAGE and run:

PATH="$PWD:$PATH" runqemu seco-clea-os-image-qemu*.rootfs.local.qemuboot.conf slirp

In this case make sure you have the right qemu system binaries installed in your local environment.

This class:

• adds the necessary dependencies (qemu, u-boot, bootscript, ovmf)
• sets up the QB_* variables to generate the correct .qemuboot.conf file for the image:
  • image type: wic
  • bios: (u-boot on arm, ovmf on x86)
  • drive type: virtio
• create the EFI System Partition on x86
• install kernel image and bootscript files to the boot partition
• .local.qemuboot.conf file, useful for running qemu from outside of the bitbake environment without the yocto sdk

Also, create the qemuboot-local recipe which deploys the runqemu scripts to DEPLOY_DIR_IMAGE for convenience when using the local configuration.