Send location from Thingy91X to Firebase Realtime Database

[Zinha]

Hello, I would like to appply change in asset tracker template  FROM nrf_cloud to Firebase Realtime Database.

https://github.com/nrfconnect/Asset-Tracker-Template/blob/main/docs/common/getting_started.md#provision-device-to-nrf-cloud

Please provide how to change.