Add Airflow DAGs UI

What does this MR do and why?

This MR adds the UI to get an overview of DAGs from a users Airflow instance. It's an incubation feature coming from the Airflow SEG. Data will be pushed from a users Airflow instance using the GitLab Agent for Kubernetes.

Describe in detail what your merge request does and why.

Screenshots or screen recordings

See also the latest video update for a working example: https://www.youtube.com/watch?v=E3_YGF7Wr2k

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

1. Choose a project (in this case FlightJS) and enable the feature flag

project = Project.find(7)
Feature.enable(:airflow_dags, project)

2. Navigate to http://127.0.0.1:3000/flightjs/Flight/-/airflow/dags and verify the table is empty
3. Populate the table

[*1..20].each { |n|  ::Airflow::Dags.create :project_id => project.id, :has_import_errors => false, :is_active => false, :is_paused => true, :next_run => "2023-03-01 00:00:00", :dag_name => "Dag number %s" % n, :schedule => "Manual", :fileloc => "/opt/dag.py" }

4. Navigate to http://127.0.0.1:3000/flightjs/Flight/-/airflow/dags and verify the table has records and pagination is present

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.