Make 16.3 minimum required version to upgrade to 16.4+

Summary

As 16.3 is a confirmed scheduled upgrade stop, marking it as a stop before upgrading any further.

Acceptance criteria

• Upgrading from any version prior 16.3 to 16.4+ attempt will be prevented and output a suggestion to upgrade to 16.3 first

Previous examples:

• Make 15.11 minimum required version to upgrade ... (!6833 - merged)
• Enforcing 15.0 to upgrade to 15.x - !6126 (merged)
• Enforcing 14.10 to upgrade to 15.0 - !6050 (merged)