Ensure multiplier points calculation is preserved across migrations

[0x-r4bbit]

Currently. multiplier points are calculated and maintained in the StakeManager contract. When there's a migration to another StakeManager version, we need to ensure the state of multiplier points calculation is preserved/transferred as well.

The goal of this issue is:

• To make sure this is happening
• Provide tests that provide the point
• If applicable, provide formal verification rule