`legal_entity_id` and `legal_entity_name` mutability

[CDR-Register-Stream]

Currently legal_entity_id and legal_entity_name are un-modifiable, and once set, are expected to be immutable.

However, in the future this may not be accurate. Brand portability between legal entities is a topic under analysis and may result in these fields becoming mutable to satisfy this use case.

This issue has been raised to track this work and also advise participants that this design may be subject to change in the future.