feat(payment_method): API to list countries and currencies supported by a country and payment method type

[Aprabhat19]

Type of Change

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

Description

Make a api to fetch the countries and currencies supported by a particular connector.
This api will be used by the dashboard to restrict payment methods to specific countries/currencies.

Additional Changes

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

Motivation and Context

Closes #4163

How did you test it?

• When the filters are set for the combination of connector and payment method type

   curl --location 'http:https://localhost:8080/payment_methods/filter?connector=stripe&paymentMethodType=affirm' \
   --header 'Authorization: Bearer JWT' \
  

   {
       "currencies": [
           "USD"
       ],
       "countries": [
           {
               "code": "US",
               "name": "UnitedStatesOfAmerica"
           }
       ]
   }
  

• When the filters are not set for the given combination, we will use default filters to get the list

   curl --location 'http:https://localhost:8080/payment_methods/filter?connector=stripe&paymentMethodType=paypal' \
   --header 'Authorization: Bearer JWT' \
  

   {
       "currencies": [
           "BRL",
           "INR",
           "EUR",
           "JPY",
           "CHF",
           "USD",
           "PLN",
           "MYR",
           "PHP",
           "SGD",
           "THB",
           "SEK",
           "RUB",
           "CAD",
           "HKD",
           "CZK",
           "NOK",
           "NZD",
           "HUF",
           "GBP",
           "AUD",
           "DKK",
           "MXN"
       ],
       "countries": [
           {
               "code": "DE",
               "name": "Germany"
           },
           ...
           {
               "code": "ZA",
               "name": "SouthAfrica"
           }
       ]
   }
  

• If the filters are not set in default also, then the list of all countries and currencies will be sent
• When the filters are not set for the given combination, we will use default filters to get the list

   curl --location 'http:https://localhost:8080/payment_methods/filter?connector=stripe&paymentMethodType=paypal' \
   --header 'Authorization: Bearer JWT' \
  

   {
       "currencies": [
           "XPF",
           ...
           "ZMW"
       ],
       "countries": [
           {
               "code": "DE",
               "name": "Germany"
           },
           ...
           {
               "code": "ZA",
               "name": "SouthAfrica"
           }
       ]
   }
  

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