feat:POL token migration

[leovct]

Description

• Implement a new migration script called 7_pol_migration.js, based on plasma-bridge-update branch, that:
  • deploys POLToken and PolygonMigration,
  • adds pol, matic and polygonMigration mapping to the Registry,
  • mints POL to PolygonMigration,
  • updates the implementation of the DepositManager,
  • migrates MATIC tokens to POL on L1.
• Add a script to test standard user bridge operations:
  • Bridge MATIC/POL on L1 and receive MATIC on L2.
  • Withdraw MATIC/POL on L2 and receive POL on L1.

Other minor stuff

• Move updateContractMap to utils to share implementation between scripts.

Jira Ticket

• DVT-1036

Test

• TODO