Use atomic.Pointer instead of atomic.Value

[pellared]

I'm looking at some code that uses atomic.Value+type casts. It could use atomic.Pointer (added in Go 1.19) instead to avoid type casts, be more readable and type safe. If not, would be good to at document the decision somewhere in contributor docs.

Originally posted by @ash2k in #3723 (comment)

[MrAlias]

What else needs to be done for this issue?

[dmathieu]

Closing this, as per #3926, we won't be switching every other occurence of atomic.Value to atomic.Pointer, due to the low impact this has.