a8n: Fetch Bitbucket server build status
Created by: ryanslade
a8n: Fetch Bitbucket server build status
Unfortnately this requires an extra two http requests per pull request
as we need to fetch commits and then fetch build status per commit.
Hopefully we can mitigate this with work to sync pull requests less
often.
Also note that Bitbucket server currently does not support webhooks for
build status. It is only supported for Bitbucket cloud.
Related to: https://github.com/sourcegraph/sourcegraph/issues/7093