Use GraphQL API from Gitlab to find jobs dependencies in a pipeline.
E.g: Find all dependencies for jobs starting with "iris-"
```sh
.gitlab-ci/bin/gitlab_gql.py --sha $(git -C ../mesa-fast-fix rev-parse HEAD) --print-dag --regex "iris-.*"
```
Signed-off-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17791>
