[dev.regabi] cmd/compile: rename ir.Find to ir.Any and update uses

ir.Find is called "any" in C#, Dart, Haskell, Python, R, Ruby, and Rust,
and "any_of" in C++, "anyMatch" in Java, "some" in JavaScript,
"exists in OCaml, and "existsb" in Coq.
(Thanks to Matthew Dempsky for the research.)

This CL changes Find to Any to use the mostly standard name.

It also updates wrapper helpers to use the any terminology:
	hasCall -> anyCall
	hasCallOrChan -> anyCallOrChan
	hasSideEffects -> anySideEffects

Unchanged are "hasNamedResults", "hasUniquePos", and "hasDefaultCase",
which are all about a single node, not any node in the IR tree.

I also renamed hasFall to endsInFallthrough, since its semantics are
neither that of "any" nor that of the remaining "has" functions.

So the new terminology helps separate different kinds of predicates nicely.

Change-Id: I9bb3c9ebf060a30447224be09a5c34ad5244ea0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/278912


Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>