Pass panics and errors to `tracing`

[m4tx]

We already handle errors and panics in the request handlers - they should never crash the application and should just display an error page instead. It would be nice to make more use of it - specifically, the errors and panics should be logged using the tracing crate, ideally with as much metadata as possible.

The main reason to do this is to allow us to integrate with tracing-opentelemetry, which will enable Cot users to monitor errors happening in their services.

The main entry point to error handling is https://github.com/cot-rs/cot/blob/master/cot/src/error_page.rs.

[mandarvaze]

@m4tx can you add details ? since you have added good first issue tag, someone other than yourself will need more information (pointer to code where you expect the change would also be helpful)

[m4tx]

@mandarvaze updated the issue description with the details, hope this helps!