[error-reporting] Support httpRequest and user context

[mpskovvang]

It is currently not possible to provide httpRequest or user context without extending the Boostrap class.

Could we have an option to provide those at initialization or using a callback? Perhaps a default implementation for httpRequest could be included with variables from $_SERVER.

Source: https://cloud.google.com/error-reporting/docs/formatting-error-messages#json_representation

[igoooor]

I'm also interested in such feature.