time: add space padding layout strings(using underscore) for not only day but others
As mentioned in #22802, only day component of layout string has space
padding(represented by one underscore before its placeholder). This
commit expands the rule for month, hour, minute and second.
Updates #22802 (maybe fixes it)
Change-Id: I886998380489862ab9a324a6774f2e4cf7124122
Reviewed-on: https://go-review.googlesource.com/78735
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Rob Pike <r@golang.org>