Ios sharing intent

[CTimmermann]

Closes #76

[CTimmermann]

Quick explanation for the changed line in _DocumentRouteState.uploadSharedDocument():

This is a workaround for some faulty behavior of the receive_sharing_intent plugin.

Without the Uri.decodeFull(), filenames including spaces or German "Umlaute" cause errors (see KasemJaffer/receive_sharing_intent#97).

The replaceAll('file://', '') is necessary due to the behavior discussed here: https://stackoverflow.com/questions/72767865/flutter-receive-sharing-intent-share-pdf-with-ios

[bauerj]

Thank you! I'll merge this into the ios branch for now, as I assume it's not ready for production yet.

[bauerj]

I'll also have to test whether the file sharing still works in Android with your replaceAll('file://', '') change. Otherwise we'll have to make that one conditional on OS.