[dev.typeparams] cmd/compile: record more typ/fun info for dictionaries in unified IR

Records whether a derived type is needed at run-time as well as
instantiated functions that rely on derived types (and thus need
sub-dictionaries).

Change-Id: I2f2036976bfce5b3b4372fba88b4116dafa7e6b7
Reviewed-on: https://go-review.googlesource.com/c/go/+/334349


Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>