DRY: Move all 3GPP common models to common-src
Issue
We have 3GPP models from TS 29.571 in all NFs with different versions.
Solution
We should all models which are reused over multiple NFs in common-src
The codebase for this oai/cn5g repository has officially moved to GitHub. Read the full migration announcement and details (https://github.com/orgs/openairinterface/discussions/3).