time: quote original value in errors returned by ParseDuration

Quote original values passed as substring of ParseError.Message.
Improves the user experience of ParseDuration by making it
quote its original argument, for example:

   _, err := time.ParseDuration("for breakfast")
 will now produce an error, which when printed out is:

  time: invalid duration "for breakfast"
 instead of:

  time: invalid duration for breakfast

Adapt test cases for format.Parse and format.ParseDuration.

Fixes #38295

Change-Id: Ife322c8f3c859e1e4e8dd546d4cf0d519b4bfa81
Reviewed-on: https://go-review.googlesource.com/c/go/+/227878


Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>