[dev.typeparams] cmd/compile: start translating type params in noder2

Also, make some fmt changes so that the type parameters and the
typeparam type are displayed in -W=2.

You can now parse a simple generic function (but not generic calls or generic
types) and print out the noder IR via 'go tool compile -G=2 -W=2 func.go'

Change-Id: I1f070fc4a96174a447763ad37999e61c25905901
Reviewed-on: https://go-review.googlesource.com/c/go/+/287833


Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dan Scales <danscales@google.com>
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>