Guide on mTLS should include an additional dependency

[azurvii]

Describe the bug

SecurityIdentity seems to require the quarkus-security dependency, for mTLS at least. Without it, explicitly or implicitly, the injection would fail with UnsatisfiedResolutionException. I got around the error by adding the dep, following the suggestion in https://github.com/quarkusio/quarkus/discussions/25122#discussioncomment-2629571.

I suggest to mention the need for the dependency (I don't know if quarkus-security is the lowest-level key dependency; but looking at its transitive dependencies, this looks most appropriate). This could save hours for other new comers, like me.

An alternative, a better one if feasible, is to include the common cause in the UnsatisfiedResolutionException thrown, stating that it's possibly missing quarkus-security (or something else that is actionable).

Which pages

https://quarkus.io/guides/security-authentication-mechanisms-concept#mutual-tls