Will bundle resources/ for viewer (and skps/ if
that directory exists in the main Skia directory).
Also updates file code on iOS to fall back to bundle directory.
Docs-Preview: https://skia.org/?cl=76803
Bug: skia:7339
Change-Id: I244f67559c866451a6d02c3f1c4948d89457ec84
Reviewed-on: https://skia-review.googlesource.com/76803
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
