[ add ] more properties of Data.List.Relation.Unary.All.Null

[jamesmckinna]

Prompted by #3084 these seem the most important additions to make.

[silas-hw]

Should this be merged first and then rebased/merged into #3084?

[jamesmckinna]

Should this be merged first and then rebased/merged into #3084?

Well, that's one way to go but up to the reviewers. V3.0 is a moving target, so some refactoring/rebasing is... inevitable before the 'new' contributions stabilise. It'll all come out in the wash ... so no need to commit one way or another right now!

UPDATED that said, @silas-hw

• I'd be happy for these to merged sooner, and then you could use the lemmas, rather than have to replicate them as in the current evolution of Add Queue datatype #3084
• in general, if you find in the course of developing such a PR that you need additional 'infrastructure' lemmas in other parts of the library, you should feel free to make such things part of the PR; but there's always inevitably some judgment call to make about what/where/when with such refactoring...