Add UMAC (RFC4418) to Cryptography Registry

[Mehrn0ush]

UMAC (RFC4418) is a standardized message authentication code (MAC) but is currently missing from the CycloneDX Cryptography Registry (schema/cryptography-defs.json).

Proposed change:

• Add a new registry entry for UMAC with reference to RFC4418.
• Add variant pattern for explicit tag sizes:
  • UMAC-32, UMAC-64, UMAC-96, UMAC-128

Rationale:

• Improves completeness and interoperability of cryptography registry.
• Non-breaking, additive registry entry only.

Reference:

• RFC4418: https://doi.org/10.17487/RFC4418