[ZP-6167] Support Android Scoped Storage

[davidofwatkins]

Android 10 introduced a new permissioning model called Scoped Storage for accessing files. Apps targeting Android 10 (API 29) can keep legacy permissioning until targeting Android 11 (API 30).

This doesn't affect files selected using the OS's default image/video/file pickers like Zenput's video and document fields. The gallery picker supported by this plugin, however, does need to adhere to the guidelines of Scoped Storage.

There's a lot of documentation out there about what changes need to be made. The short of it is to access files by their content URIs rather than absolute file paths. (Still, file paths may continue to work in some cases.) In the context of this plugin, that meant:

• Referencing files with ContentUris.withAppendedId(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, <file ID>) instead of MediaStore.Images.Media.DATA
• Loading images with BitmapFactory.decodeFileDescriptor() and getApplicationContext().getContentResolver().openFileDescriptor(<uri>) instead of just BitmapFactory.decodeFile(<absolute path>)
• Determining a file's name with getContentResolver().query() and mime type with getContentResolver().getType(<uri>) instead of instantiating a File and guessing based on extension.

This was one of the blockers for targeting the Android 30 API level (required by Google in November), so this should relieve some headaches in the future when we make that change in Zenput.

This also adds NPM scripts for more easily publishing (draft) releases to NPM. (No CI automation yet!)

Resources on Android's Scoped Storage::

• Scoped Storage in Android 10 & Android 11
• Storage updates in Android 11
• Preparing for scoped storage (Android Dev Summit '19)
• Preparing for Scoped Storage

[sfcoons]

looks good to me - nice work!