cmd/compile/internal/inline: add framework to compute func "properties"

cmd/compile/internal/inline: add framework to compute func "properties"

Add some machinery to support computing function "properties" for use
in driving inlining heuristics, and a unit testing framework to check
to see if the property computations are correct for a given set of
canned Go source files. This CL is mainly the analysis skeleton and a
testing framework; the code to compute the actual props will arrive in
a later patch.

Updates #61502.

Change-Id: I7970b64f713d17d7fdd7e8e9ccc7d9b0490571bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/511557
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>