fix(android): return error if file url is null

[jcesarmobile]

Platforms affected

android

Motivation and Context

When picking files from the gallery, sometimes it can return "null" as the path, but on the success callback.
This PR will call the error callback if the file path is null (might be breaking if people is expecting null result for some reason?)

The PR also unify the logic, since at the moment this code returns a file url

navigator.camera.getPicture(onSuccess, onFail, { quality: 50,
     destinationType: Camera.DestinationType.FILE_URI,
     sourceType: Camera.PictureSourceType.PHOTOLIBRARY,
     targetWidth: 1024,
     correctOrientation: true
});

but this code returns a content url

navigator.camera.getPicture(onSuccess, onFail, { quality: 50,
     destinationType: Camera.DestinationType.FILE_URI,
     sourceType: Camera.PictureSourceType.PHOTOLIBRARY
});

The PR will try to return a file url if available, and if not available, the content url. (and the error if none is available)
So, some cases where the url was null, won't be anymore.

closes #368 as it will return a file url if available

Description

note: use the "Hide whitespace changes" github option for easier review, the code changes are very small

Testing

tested on real android devices with the code provided

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[jcesarmobile]

I will merge on Thursday if nobody has reviewed by then

[erisu]

Code Changes LGTM 👍