Improve logging/error handling for Java/.NET services

[ammerzon]

Is your feature request related to a problem? Please describe.

• Most of the logging doesn't print any timestamps or affected line numbers.
• Frontend logging is too verbose in error cases

Definition of Done

• [ ] A proper logging framework for all services is used
• [ ] The logs are consistent across services and contain timestamps and class/code location if possible
• [ ] The console is not spammed when errors are thrown

Tasks

• [ ] Try out unguard under normal load and observe logs (to spot spam/bad logs)
• [ ] Adjust logs of the microblog-service
  • Java, SL4J
• [ ] Adjust logs of proxy-service
  • Java, Log4J (don't change that)
• [ ] Adjust logs to ad-service
  • .NET, add a framework. If not included, look up best practices
• [ ] Ensure quality and functionality
  • Manual tryout, tests, warnings, code-style

Additional context

• The frontend tends to spam unreadable loglines when other services crash/are not available
• Stick to logging format already present in e.g microblog-service