Run checks & tests in GitHub Actions on every push

- Separate workflows for min & max supported OTP version
- Multiple groups for clustering_management (run in parallel & finish quicker)
- Store CT logs as artefacts on failure
- Tests badge in README
- Store in S3 the version of the RabbitMQ components used while testing

We have decided to not not run tests for RabbitMQ components that we
depend on: rabbitmq-cli, rabbitmq-erlang-client & rabbitmq-common.
rabbitmq-cli & rabbitmq-erlang-client depend on rabbitmq-server
(recursive dependency) meaning that they will clone rabbitmq-server
again, inside the deps dir. We will continue to run these in Concourse,
until we merge all repositories into a single one. Let's be honest, it's
a monolith!

Signed-off-by: Gerhard Lazu <[email protected]>

Author: gerhard

.github/CODEOWNERS

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+.github/workflows/ @gerhard @dumbbell