[firebase_storage] Don't retry / backoff when offline

[oodavid]

Is your feature request related to a problem? Please describe.
I've noticed that uploads don't resume gracefully after device network has been reactivated.

• The user turns Airplane mode on to preserve battery / save money
• The app makes FirebaseStorage..putFile requests regardless of network state
• After a couple of hours, the user turns Airplane mode back off
• Any pending Uploads don't resume

I assume they don't resume as they've hit some limit in number of retries, or the exponential backoff is too big.

Describe the solution you'd like
I'd like the upload task to retry with initial values when data / WiFi has been reactivated.

Additional context
none