WIP: Integration testing of AIStor MinIO APIs through madmin clients

[JoelRuizRojas]

Adding integration testing of AIStor MinIO APIs hit through madmin clients

Content:

1. Makefile targets to prepare for and run integration tests
2. CI/CD pipeline to automatically run integration tests on every PR to main branch in this repo, and periodically (still pending) to cover API changes from miniohq/eos repo.
3. README.md documentation that explain the integration testing strategy.
4. A integration test example

[JoelRuizRojas]

Based on last discussion with Kannappan, seems that there will be a private madmin-go repo with latest content from this one. So since some GitHub secrets are needed to run the GitHub workflow, we decided to wait for the new repo to be created (apparently within a few days). So I will be migrating this PR to that new repo.