[release-branch.go1.21] net/mail: properly handle special characters in phrase and obs-phrase
Fixes a couple of misalignments with RFC 5322 which introduce
significant diffs between (mostly) conformant parsers.
This change reverts the changes made in CL50911, which allowed certain
special RFC 5322 characters to appear unquoted in the "phrase" syntax.
It is unclear why this change was made in the first place, and created
a divergence from comformant parsers. In particular this resulted in
treating comments in display names incorrectly.
Additionally properly handle trailing malformed comments in the group
syntax.
For #65083
Fixes #65848
Change-Id: I00dddc044c6ae3381154e43236632604c390f672
Reviewed-on: https://go-review.googlesource.com/c/go/+/555596 Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/566195 Reviewed-by: Carlos Amedee <carlos@golang.org>