Add full support for fee handlers in migration scripts

[MakMuftic]

Current support for deploying different fee handlers trough migration scripts is limited. This could be especially become a hurtle on deploying new networks in production like environments (with a need for deploying and configuring multiple fee handlers on initial deployment).

Implementation details

To enable deployment of multiple fee handlers and using them when registering on fee router, requires an significant refactor of migration config file format. Below is one possible approach to new format that would enable us to:

• define multiple fee handler instances that need to be deployed
• map different fee handlers for each resource (per destination domain)

{
    "fee": {
        "basic": ["0.1", "0.2"],
        "oracle": [
            {
                "target": "evm",
                "gmp": true,
                "params": {
                    "gasUsed": "",
                    "feePercentage": 0
                },
                "address": ""
            }
        ]
    },
    "erc721": [
        {
            "name": "ERC721",
            "fees": [
                {
                    "destDomainID": "5",
                    "feeHandler": "oracle-0"
                },
                {
                    "destDomainID": "2",
                    "feeHandler": "basic-1"
                }
            ]
        }
    ]
}

Testing details

• Manually test executing initial migration with multiple fee handlers defined, and different fee handlers registered for same resource.

Acceptance Criteria

• Migration scripts have full support for deploying and setting fee handlers