scripts/run_archiso.sh:
Add the `-a` option flag to add accessibility support on demand for `run_archiso`.

Not providing the specific braille chardev (hardware?) otherwise blocks running run_archiso with
`qemu-system-x86_64: -chardev braille,id=brltty: brlapi__openConnection: connect: No such file or directory`.

Fixes #77

forgot to enable USB support.

necessary for testing brltty in archiso

also included serial output on stdio it helps in debugging without sight.

Use virtio-scsi to attach the image. virtio-blk (if=virtio) is inconsistent about the used media type.

ISO testing doesn't require the emulated firmware's PXE stack.
For UEFI, it only disable iPXE in favor of EDK II network stack. https://github.com/tianocore/tianocore.github.io/wiki/EDKII-Network-Over-QEMU#verification-result

Various bash script improvements.

scripts/run_archiso.sh:
A script to run a built archiso image using qemu.
It can run the image on an emulated BIOS (using seabios) or UEFI (using edk2-ovmf) system.

.gitlab-ci.yml:
Adding scripts/run_archiso.sh to shellcheck call.

Closes #28