[auth_service] Define buildbucket.creator role
[auth_service] Define buildbucket.creator role

Bug: 1114804
Change-Id: I87a315b493bf5b34f51061a05cabaa8766173834
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/3988373
Commit-Queue: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py