[FR] Add support to realtime database for Variants containg Blobs

### Feature proposal

* Firebase Component: Database

Describe your use case and/or feature request here.

Add support for Variants containing Blobs. Or at least provide best practices for storing binary data.

Start by locating the Realtime Database implementation and its handling of Variants, then clarify whether the intended outcome is Blob support or best-practice documentation for binary data. Done should mean one of those outcomes is explicitly defined and implemented or documented, with validation for the chosen behavior.

Written by the indexing model from the issue text.