CONTRIBUTORS: update for the Go 1.19 release

CONTRIBUTORS: update for the Go 1.19 release

This update was created using the updatecontrib command:

	go install golang.org/x/build/cmd/updatecontrib@latest
	cd gotip
	updatecontrib

With manual changes based on publicly available information
to canonicalize letter case and formatting for a few names.

For #12042.

Change-Id: I5e648b99004026513c5772b579a72b7add970db4
Reviewed-on: https://go-review.googlesource.com/c/go/+/418016
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Run-TryBot: Carlos Amedee <carlos@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>