Added skstd::string_view

Change-Id: Id02ed33b4fe60663327cc50d79db2bf876ad6df7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/415458
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
6 files changed