improve error dialog

[scheidtdav]

Description

The current implementation of the error dialog states "add info here" which sounds like its requesting the user to add information to it. It also claims that the team is working on it, even though we have no way of knowing.

Instead it should provide a clear indication of what went wrong (e.g. an exception message) and on how to file a bug report/ how to proceed with the issue.
Being able to copy console output or a stack trace would be a nice addition too.

Use case

Users of all kind will benefit from this, including developers which get more relevant bug reports.

Implementation ideas (optional)

error-message.tsx needs to be changed to include links to the github project and clear instructions on how to proceed when an error occurs.

Route.ErrorBoundaryProps can be used to pass context to the error boundary in order to enrich it with the necessary context.

Additional information (optional)

As some additional refactoring: we don't seem to need error boundaries in so many files (like we have right now), since it seems to bubble up the navigation tree.
Hence, one definition of the error boundary in app.tsx should probably be enough and all the others can be deleted.