Ability to use auth.currentUser (or other user state mechanism) rather than onAuthStateChanged

[Uncodeable864]

The way to get users leads to having to write callbacks in every file. Due to the fact that auth.currentUser returns a value (not a Promise like a large proportion of the API. So, my feature request/idea is a separate getUserLoaded function that would return true only if the user object is loaded (false is still loading). This would allow the code to be unlittered with onAuthStateChanged callbacks, and allow it to look much, much cleaner. Another solution is that the currentUser variable could have a type of User | 1 | undefined. The variable's value would start off at 1, and continue from there.