Use this endpoint to change the ID that identifies one of your Contexts.
This should be used primarily for migration, if the IDs in your application (and particularly the IDs on your tokens) change.
Note that calling this endpoint while a user is active on Xkit could potentially cause issues:
- if the new Context ID already exists, this call will fail
- if the user is logged in during the migration, they may inadvertently recreate a Context under their old ID