[FR] A better and more explicit way to close and end firebase connection

[AllyssonAlas]

Is your feature request related to a problem? Please describe.
After a few searchs I didn't find a way to properly close a connection with firebase . The API itself has this method "deleteApp" which disables the received firebase connection, but somehow this connection keeps active in memory, firebase docs (https://firebase.google.com/docs/reference/admin/node/firebase-admin.app.md#deleteapp) say it is the proper method to finish the connection locally, but also say it doesn't clean any "back end resource" which it is not clear.

Describe the solution you'd like
How about a method that really turns off the connection and clears the value of the client in memory.

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