JupyterLab 3.0: bump image prefix across the federation

[minrk]

The order these things should be done in (they can be simultaneous, but some should not be before others):

1. update jupyterlab default UI in repo2docker (merged Default UI to JupyterLab repo2docker#1035)
2. invalidate image cache by bumping image prefix (this pr). Cache should be invalidated with/after the r2d bump so we can assume new builds have lab 3.1.
3. bump binderhub filepath handling to use jupyterlab Send filepath urls to JupyterLab instead of classic notebook binderhub#1288 . This change is where we start to apply the assumption that cached builds have jupyterlab 3, and provide consistent UI for both filepath and default URLs.

This PR currently does all 3 (includes #2011 and #2014)

Purging the image cache means lots of new builds, and we will probably want to sweep out our old cache (related: #2012)

[consideRatio]

Thanks for your work on this Min! This LGTM!

As discussed in a video chat:

• Min plan to deploy this to staging and try it out there.
• We want to clean up images. Currently, we do that manually with a search of images to be cleaned based on their name that doesn't match the new prefix. This is not essential to do directly or similar, but an action point of relevance to get done.

Loose thoughts:

• Use launch data...
• Limiting the number of builds per repo (each has a specific SHA)
• It could be nice to see the available SHA for a repo

[minrk]

/test-this-pr

[minrk]

/test-this-pr

[sgibson91]

This Pull Request is now being tested 🎉 See the test progress in GitHub Actions.

[minrk]

/test-this-pr

[sgibson91]

This Pull Request is now being tested 🎉 See the test progress in GitHub Actions.

[sgibson91]

Sidebar: We might need give the GITHUB_TOKEN extra permissions or use my token in the report_status job to avoid these errors

Error: Unhandled error: HttpError: Resource not accessible by integration

[minrk]

@sgibson91 yes! I was just writing a note about that. Deploy worked great, up to the delete & post-after-done steps, which need permissions.

[minrk]

/test-this-pr

[sgibson91]

This Pull Request is now being tested 🎉 See the test progress in GitHub Actions.

[minrk]

/test-this-pr

[sgibson91]

This Pull Request is now being tested 🎉 See the test progress in GitHub Actions.

[minrk]

okay, finally got it. Links to test on staging, all do what they are supposed to:

• regular binder link, default url
• with filepath
• urlpath to opt-in to /tree

[minrk]

Since this is disruptive and my day is ending, I'll deploy this to prod, tomorrow AM