Fix PDF preview on Android devices

This is probably linked to NXMOB-519 as react-native-pdf uses react-native-fetch-blob, upgrading the version on our side broke react-native-pdf.

We should update react-native-pdf to the latest version and use the new rn-fetch-blob instead of the unmaintained react-native-fetch-blob.

This may cause other issues where we use react-native-fetch-blob such as downloading a blob, sharing a file, ..., so it needs to be well tested before releasing the app.