FR: Allow uploading of local files to Storage in Electron Apps

### [REQUIRED] Describe your environment

* Operating System version: MacOS Mojave 10.14.3
* Browser version: Google Chrome Version 77.0.3865.90 (Electron)
* Firebase SDK version: 6.6.0
* Firebase Product: Storage

### [REQUIRED] Describe the problem
I am writing an Electron app, and I have run into a problem uploading files to Firebase storage. I have the user chose a path to a file, and then attempt to upload the file to firebase storage. I know that the firebase storage web SDK can upload blobs, and that the `@google-cloud/storage` module is able to upload based on filename (although I haven't found a way to get snapshots like those that are part of the uploadTask in firebase). I know that the IOS and Android SDKs are able to upload based on file paths, so I am wondering if it is possible to implement this in the javascript SDK. I am aware that there are security issues with this, but I think that adding support for this in native node apps such as electron would be very helpful. Thank you!