As per discussion in #401 and gerrit I have built out the proposed endpoint package.
I migrated all the existing endpoints, not sure if you wanted this but it does illustrate the pattern.
Change-Id: I53f56a06207633b2380b7cd7332cd56f9ef6578f
GitHub-Last-Rev: fde9e7bb75
GitHub-Pull-Request: golang/oauth2#402
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/212223
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>