Validate glyph size before insetting for atlases Bug: b/501483855 Change-Id: I27f4201a80238ebbbdf74b45403deda5e5c744ee Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1221677 Reviewed-by: Thomas Smith <thomsmit@google.com> Commit-Queue: Michael Ludwig <michaelludwig@google.com>