[llvm] [STLExtras] Introduce bind_{front, back}, [not_]equal_to (PR #175056)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

This looks like a very handy general utility to have available! I assume there are a number of other places that could also benefit, would be great to see them also converted in follow-ups!

LGTM on the overall approach, would be good wait for another approval.

https://github.com/llvm/llvm-project/pull/175056