Allows immutable cache for static files in a directory

[brichet]

As mentioned in jupyterlab/jupyterlab#10273 and jupyterlab/jupyterlab#14124, JupyterLab now uses hashes for the javascript assets.

This PR allows to serve static files as immutable to avoid server requests (when the static files have no-cache header), by setting up the setting "static_immutable_cache".

Additional context:
Discussed in weekly meeting jupyter-server/team-compass#45 (comment)

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[blink1073]

LGTM, thanks!

[welcome]

Congrats on your first merged pull request in this project! 🎉

Thank you for contributing, we are very proud of you! ❤️

[brichet]

@meeseeksdev please backport to 1.x

[lumberbot-app]

Awww, sorry brichet you do not seem to be allowed to do that, please ask a repository maintainer.

[brichet]

Should it be backported to 1.x ?

[blink1073]

@meeseeksdev please backport to 1.x

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 1.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 54d72923949a506375c522193b41b3cff3aaa79f

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #1268: Allows immutable cache for static files in a directory'

4. Push to a named branch:

git push YOURFORK 1.x:auto-backport-of-pr-1268-on-1.x

5. Create a PR against branch 1.x, I would have named this PR:

"Backport PR #1268 on branch 1.x (Allows immutable cache for static files in a directory)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.