feat(pm_list): add pm list support for voucher

[swangi-kumari]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

How did you test it?

In Adyen do payment connector create with having voucher payment_methods_enabled enabled

`{
            "payment_method": "voucher",
            "payment_method_types": [
                {
                    "payment_method_type": "boleto",
                    "minimum_amount": 1,
                    "maximum_amount": 68607706,
                    "recurring_enabled": true,
                    "installment_payment_enabled": true
                }
            ]
        }`

Then list payment methods for merchant , we should get "payment_method": "voucher", inside payment_methods

 "payment_methods": [
        {
            "payment_method": "voucher",
            "payment_method_types": [
                {
                    "payment_method_type": "boleto",
                    "payment_experience": null,
                    "card_networks": null,
                    "bank_names": null,
                    "bank_debits": null,
                    "bank_transfers": null,
                    "voucher": {
                        "eligible_connectors": [
                            "adyen"
                        ]
                    },
                    "required_fields": null,
                    "surcharge_details": null,
                    "pm_auth_connector": null
                }
            ]
        }
    ],

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible
• I added a CHANGELOG entry if applicable

[swangi-kumari]

This feature already exist, so closing this PR.