[FEATURE REQUEST] Media model should support saving to S3/GCP URLs

[evanderiel]

Feature Summary

• The Media model should support saving to S3/GCP URLs

Justification/Rationale

• Makes it easier to deploy SDK in cloud-native environments
• If we have a public demo cloud block storage is cheaper and easier to manage than having to grow virtual disks

Proposed Implementation (if any)

• Define a MediaStorageAdapter class that can be subclassed for S3, GCP, etc
• Use environment variables or settings to dictate which, if any gets used and to set credentials.

[movchan74]

@evanderiel please add title