Tighten typehint in UserSession::hasPermission() and User::hasPermission()

I reviewed this issue because I was doing triage on the originating issue.

The issue summary here should be more helpful. It should explain what work is to be completed here. As it is, a contributor has to read the parent issue and the change there first. And hopefully, they will find comment #19 over there that links to the deprecation policy that explains part of the process.

Also, the standard template should be restore so that all sections are available. Those sections are helpful in many ways. It is the first thing someone a contributor see when deciding to work on an issue so it should be inviting and explain the work clearly. It is also how we track of what work has been completed and what still needs to be done. And, speaking for myself, it is too often that I have to restore the template so I can complete a review. I'd rather not have to do that.

Typically, I summarize the remaining work in the remaining tasks section but I will do so here.

1. Restore the standard issue summary template →
2. Complete the template, explaining clearly what work is to be done here. Add link to the correct section of the Deprecation Policy.
3. Consider tagging as Novice.

As blocker merged, tuned IS a bit

Seems to have test failures.

Looks like return-type needs more work in unit tests

Added a comment inline in the MR.

Core maintainers, do you agree with mondrake's comment about the return type?

10.3 has shipped already and it feels a bit odd to patch in a return type hint right before the release of 11. I would rather we drop the return type hint altogether and stick to the bare essentials: typehint the permission as a string and enforce this in 11.x

For that matter, we need to be quick about this too as 11.0 is to be release this week.

Seems like this was fixed in 📌 Remove deprecated code from user module Fixed