* pkg/web: store http.Handler internally
* pkg/web: remove injection
Removes any injection code from pkg/web.
It already was no longer functional, as we already only injected into
`http.Handler`, meaning we only inject ctx.Req and ctx.Resp.
Any other types (*Context, *ReqContext) were already accessed using the
http.Request.Context.Value() method.
* *: remove type mappings
Removes any call to the previously removed TypeMapper, as those were
non-functional already.
* pkg/web: remove Context.Invoke
was no longer used outside of pkg/web and also no longer functional
