Apple fixes for app launch exception, vodozemac and emoji (4/4)

[zeyus]

This supersedes #837

• Vodozemac does not initialize unless you use the correct init method from flutter_vodozemac
• Fixes an exception that consistently occurs during app launch (probably to do with isolate task scheduling)
  • Just wrapping the async functions in closures is enough to prevent the error
  • This additionally adds a more informative error log if something does go wrong in the isolate
• For apple platforms, use system emoji, the emoji font does not render (i also tried TTF instead of OTF but it didn't make any difference)