Enhancement: Improved Handling FCM tokens

[gkatrakazas]

FCM Token Handling During Signup:
We should enhance our signup process to remove the storing FCM token because the store now being after signup/login.

Delete invalid FCM token when try to send notification.

In the following code, we should handle the FirebaseMessagingError with the message 'Requested entity was not found.' This error may indicate that the FCM token has expired or been deleted, so it's advisable to handle this situation by deleting the invalid token.

https://github.com/wwWallet/wallet-backend-server/blob/9d9597632085301528f0d4c6b0aa6a2a560ec170/src/lib/firebase.ts#L42C1-L48C7

admin.messaging().send(message)
        .then((response) => {
        console.log(response + ' messages were sent successfully');
        })
        .catch(err => {
                console.log("failed to send firebase message")
        });