Support wildcards in keypath notifications

[cmelchior]

This is an extension to #7087

Users of the SDK are currently using an API that looks something like this

val keypaths = listOf("name", "age", "child", "child.age", "child.name")
results.add_notification_callback(keypaths, callback)

For a limited number of properties, this is fine, but it quickly becomes unmanageable for larger object graphs. For this reason, it would be nice if the keypath method introduced in https://github.com/realm/realm-core/pull/7087/files#diff-26d19337fc5c7d539cf862de4f09e38ea8b514402b48349adb3713832aee5518R50, would be able to handle * as a wildcard property and automatically expand any object references or object lists/sets/maps.

E.g. given this object graph:

class Person: RealmObject {
  var name: String
  var age: Int
  var children: RealmList<Child>
}

class Child: RealmObject {
  var name: String
  var favoritePet: Pet?
}

class Pet: RealmObject {
  var name: String
  var type: String
}

You could register a wildcard keypath like *.*.* which would be equal to listOf("name", "age", "children", "children.name", "children.favoritePet", "children.favoritePet.name", "children.favoritePet.type")

Wildcards should only expand valid paths and ignore an expansion that isn't valid, i.e. children.*.type would only match children.favoritePet.type because it would be the only correct path matching the expanded path.

As a sidenote, the current implementation in the notifier is equivalent to *.*.*.* since we only detect changes 4 nested levels down.