Add support for tracking changes to CleverTap ID after the kit started

[johannsa]

We need to add support to the kit to track changes to the CleverTap Id during the application lifecycle, not just during the kit start.

These would be relevant in two circumstances:

• After user logged in (relevant code)
• After user changed their identities (relevant code)

That way, the CleverTap partner Id would be accurate and a "freshly" logged in user would not have on its profile the CleverTap Id of the previous user on the device.