Add Graviton to Github CI OpenCL CTS planned testing

[alan-forbes-cp]

Overview

Add aarch64 Graviton to Github CI OpenCL CTS planned testing

Reason for change

Replace current qemu-based workflow

Description of change

• Add new graviton dockerfile.
• Update publish job in docker workflow for graviton
• Add new runs-on: and image: config to OpenCL CTS job for graviton.
• Remove qemu setting from OpenCL CTS aarch64 run job
• Host target lists and image config were refactored as they had become difficult to read.
• Dockerfiles and corresponding image names have been updated to reflect the arch.

Anything else we should know?

• Test results are the same as qemu (and Gitlab)
• Note that some temporary changes which were added to limit the number of jobs that run during development will be removed prior to final merge.
• Similarly the new docker image for aarch64 OpenCL CTS will be pointed at uxlfoundation rather than the current development registry.