Support the ability to promote extensions to core without breaking changes

[alanisaac]

Background

Extensions have some great characteristics for prototyping new OCSF schema:

• They allow for individuals to iterate on schemas without needing consensus from OCSF maintainers on code reviews to include them in the core schema.
• They are consumable by end-users, which allows schema designers to solicit feedback on the utility of the schema.

However, it is not possible to cleanly "promote" extensions to core. The UIDs for categories, classes, etc. change between extension schemas and core schemas, which constitutes a breaking change.

Example

This was noted on the 2024-10-22 working group call: extensions could be a way to prototype and iterate on an "IoT" category before inclusion into the schema, but it would be challenging to migrate that category to OCSF core.

Proposal

This issue proposes that we try to either:

• create a path for extensions to become a part of OCSF core without breaking changes
• support an alternative path for iteration with similar characteristics