Allow for outgoing error reporting using GLOBAL_ERROR_HANDLER / set_error_handler

## What problem does this solve or what need does it fill?

For automatic error reporting to be possible using the global bevy error handler, there needs to be a way to send out errors from the ErrorHandler function. Currently this is not possible, since the ErrorHandler type does not accept closures, and does not give access to the world.

## What solution would you like?

Give world access in the ErrorHandler function, or allow for closures to be used as ErrorHandlers, so that a channel can be captured and used to send out error information.

## What alternative(s) have you considered?

The alternative is piping every single fallible system into an error handler, which seems like the exact thing a global error aims to solve.