Enforce TLS Integration

[dariofaccin]

Description

Enforces TLS integration in the charm. Charm remains in blocked state until the certificates relation is created, and in waiting status until a certificate is stored.

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

[DanielArndt]

@dariofaccin I didn't do anything here. I just re-ran it after the first build on my commit failed -- under the suspicion that maybe something cached on the runner. I'm not sure that makes any sense... but it succeeded this time...