Show dag parsing stats to user in UI view

[dstandish]

Body

How long it takes to parse a dag is really important, but really hard for users to see.

We need to expose this to users so they can see what are the problem dags. Also helpful for troubleshooting.

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[SamWheating]

👋 I am interested in taking a stab at this feature - I have been meaning to get more hands-on with Airflow 3, and haven't been doing as much OSS stuff lately.

Would it make sense to just display this parsing_duration in the code tab alongside the last_parsed_time?

My understanding of the internals here might be out of date, but I think that this would require just require adding a field to the DagModel class and exposing this in the dags/<dag>/details endpoint, + some UI changes, correct?

Feel free to assign me and I can try to put up a PR tomorrow.