aemfvp-a-rme: script for booting a lkvm distro guest in realm security state

Adding realm_distro_boot.sh for launching distro realm guest. Usecase supports
- booting FVP with stack built bins and images.
- waiting for fvp boot to complete and login prompt to appear.
- lkvm_uefi_boot_cmd to launch lkvm guest using distro image and firmware.
- waiting for distro login prompt to appear indicating successfull boot.
- use case is supporting automated runs.
- fvprun to run ssh command at FVP host.

Signed-off-by: nitin sharma <nitin.sharma3@arm.com>
Change-Id: I4fd16cf8ef80c45956638dd116a8a6e622e17424