Add bot/test.sh script and a generic test_compatibility_layer.sh script

[bedroge]

This adds a bot/test.sh script that lets the bot run the ReFrame tests on top of a compatibility layer that was just built, and also a bot/check-test.sh script that makes it report the test results back to the PR. The latter is just a copy of the one that we already use for the software layer.

To make the testing a bit easier and also allow others to easily run the tests, I've also added a test_compatibility_layer.sh script: this script is similar to the existing install_compatibility_layer.sh and runs the ReFrame tests with an existing or (temporary) pip-installed ReFrame on top of any compatibility layer that is available.

Finally, it makes a small change to the bot/build.sh script as well to fix an issue with the version number being used, in the same way as I'm doing it for the test step: the job_version variable is currently always set to 2023.06 by the bot, even though the Ansible settings may contain another value. That doesn't really make sense to me, and this PR basically just ignores the job_version and uses the value set in the Ansible settings. That allows you to open a PR and easily test things for a new EESSI version by just adjusting Ansible's default/main.yml file, instead of having to change the bot configuration.

All of this has been tested in #209, more specifically in #209 (comment).

[eessi-bot]

Instance eessi-bot-mc-aws is configured to build for:

• architectures: x86_64/generic, x86_64/intel/haswell, x86_64/intel/sapphire_rapids, x86_64/intel/skylake_avx512, x86_64/amd/zen2, x86_64/amd/zen3, aarch64/generic, aarch64/neoverse_n1, aarch64/neoverse_v1
• repositories: eessi.io-2023.06-software, eessi.io-2023.06-compat

[eessi-bot]

Instance eessi-bot-mc-azure is configured to build for:

• architectures: x86_64/amd/zen4
• repositories: eessi.io-2023.06-software, eessi.io-2023.06-compat