gddo-server: add debug logs

Additional debug messages are added to the path for redirecting requests
to pkg.go.dev.

The response body is only logged for fetch requests. For other requests,
it will be the entire HTML page.

Change-Id: I61d67e08ae24485a28fc394959a1ca3f8459b46a
Reviewed-on: https://go-review.googlesource.com/c/gddo/+/284793
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
2 files changed