💡 Append User Identity for Access Requests

**Describe the feature you'd like**
Currently, if you are using cloudflared with access verification, you have to have a proxy to retrieve the [User Identity](https://developers.cloudflare.com/cloudflare-one/identity/authorization-cookie/application-token/#user-identity) info. It would be nice, cloudflared could retrieve this information and add it as headers to the request.

**Describe alternatives you've considered**
Creating middleware that goes between cloudflared and my origin service.

**Additional context**
I could attempt to work on this if it is something that is accepted.