gddo: update from Godeps to modules

In order to ensure that full-text-search keeps running,
the google.golang.org/appengine package needs updating.

The first step of this is to convert to using modules
before updating the dependency.

Commands run:

go mod init github.com/golang/gddo
go mod tidy
go mod vendor
rm -rf Godeps

Change-Id: I6b5d1465226217bb1c0f134c90cd94aa2e7046d1
Reviewed-on: https://go-review.googlesource.com/c/gddo/+/215678
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
101 files changed