Improve Error Handling in REST Interface

[soad003]

Global error handling is currently done in the auto generated (via a template) controllers where uncatched errors are converted into http responses (e.g. https://github.com/graphsense/graphsense-REST/blob/416c96dc37ea7f1af8d88c9e6ac00d462780e4d9/openapi_server/controllers/addresses_controller.py#L74-L90).

Some exception types get special treatment like value errors and Runtime errors. They are simply ignored and a generic http status code is returned to the client. Only a stacktrace is printed to the console log and no other notifications are set up. Given that we only get notified on error logs via the python logging facility those kinds of errors usually go unnoticed.

[soad003]

The old logic reused generic exception types for signaling very specific events to the user:

• RuntimeErrors where used to signal some item was not found.
• ValueErrors where uses to signal wrong user input

Since these exception types are very generic and used by libs etc. in an uncontrollable fashion, some errors gone unnoticed (where only reported to the user). As a remedy we introduced new custom exceptions to handle the two exception cases we want to explicitly push back to the user.

• NotFoundException signals some app logic item was not found
• BadUserInputException is used to signal to users that the input was wrong.

This should avoid missing relevant errors in the REST interface.