[recipes] Move app_name into flavor.setup()

This allows us to move iOS-specific stuff from individual recipes into
the flavor module.

First in a long series of CLs to clean up recipes and move to task drivers.

Change-Id: Iff01610f76c71920639328ead5209e0cd5d93f31
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273762
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
27 files changed