Add datasource for Firebase Android App Config

[modular-magician]

Add a data source for Firebase Android App Config. Similar to firebase_apple_app_config

If this PR is for Terraform, I acknowledge that I have:

• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Generated Terraform providers, and ran make test and make lint in the generated providers to ensure it passes unit and linter tests.
• Ran relevant acceptance tests using my own Google Cloud project and credentials (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

firebase_android_app_config

Derived from GoogleCloudPlatform/magic-modules#7606