Improve mountpoint test suite

[mmmarcos]

In recent versions, we have detected several problems related to mountpoint basic operations (e.g. #8764, #8907, #8991) after the release is published. This clearly indicates that the test suite needs improvement.

What needs improvement:

• Improve libparsec mounpoint crate tests #9004
• Review and complete mountpoint test protocol #9005

Additionally, we should think about which parts of the mountpoint test protocol can be automated locally. For example, we could have a script that uses system utilities (cp, mv, rm, ...) to perform basic tests.

🍎 NOTE: mounpoint tests cannot be run on macOS in the CI because we haven't managed to install libfuse on it. Until this is fixed, a manual step should be added to run this tests during the release test campaign.