Removed StringFragment alias in favor of skstd::string_view

Change-Id: I026a8a6b452d4cb8adce4d5d4908aaf2e71f2555
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/417516
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
42 files changed