feat: retreive file mimeType from iOS

[achorein]

Summary

In order to have the same file description on iOS and Android, we need to get the mimeType from the iOS part.

export interface IosShareIntentFile {
  path: string;
  type: string;
  fileName: string;
  mimeType: string;
}

export interface AndroidShareIntentFile {
  fileName: string;
  filePath: string;
  mimeType: string;
  contentUri: string;
}

Todo

• [x] Retrieve file mimeType from file extension on iOS
• [x] Harmonize shareIntent.type for ios and android
• [x] Update README.md

Issue

https://github.com/achorein/expo-share-intent/issues/40