User-based dynamic log levels

[RemiBardon]

#191 introduces the fact that we should support changing log levels at runtime, explaining why it's important. However, turning traces on for every request can be too much in large organizations. Some tools allow enabling logs for a single user, and we could implement it if we feel the need.

Note 1: We don't need to add static configuration keys for this, until someone finds a use case.

Note 2: Even though load tests will generate a ton of logs when debugging, we wouldn't really need this feature as OpenTelemetry will allow filtering it and we can then throw everything away once we're done.

Side thought: Prose Pod APIs won't be under very high load in general, so this really isn't a priority. At least it's there if people want to talk about it or mention they would like this feature introduced.