Always document Any?

[srittau]

I'd like to propose a policy that we require any use of un-aliased Any to be accompanied by a comment described why the Any is needed. Using Any is always a bit of a red flag to me (although of course often needed), and it's often not overly obvious why Any is required. We've started to tackle this problem in the past by adding few aliases to better document the use of Any, which was a great start. But sometimes it's also not clear whether Any is really required or whether it's just a placeholder. And that situation also changes over time as the type system gains new features.

Of course, this only applies to new or changed annotations. I don't propose that we need to go through all existing Anys.

[Avasam]

Obligatory xref #9550 ^^ whilst

I don't propose that we need to go through all existing Anys.

it still prevents regressing