Remove usage of `ktx` dependencies

[shubhamsinghshubham777]

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Since the Kotlin extensions (KTX) APIs have been added to their respective main modules, this library should also drop using ktx dependencies to avoid the end-users seeing warnings/issues like:

Failed to resolve: com.google.firebase:firebase-database-ktx

Ref: https://firebase.google.com/docs/android/kotlin-migration