feat: add charm tracing support

[gruyaume]

Description

Add charm tracing support using the Observability team's tracing charm relation interface.

Rationale

Charm tracing allows developers to vizualize code paths traversed during charm events and to know the amount of time spent in each function. This is useful for both troubleshooting and performance engineering.

Usage

1. Deploy cos-lite and tempo
2. Deploy AMF K8s
3. Integrate AMF k8s with tempo

Screenshot

Checklist:

• [ ] My code follows the style guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that validate the behaviour of the software
• [ ] I validated that new and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules
• [ ] I have bumped the version of the library