Issue:
feat: create an api to get countries and currencies for a connector and pmt

Currently there is no way to set countries and currencies for a particular connector and payment method type. This api should give the list of countries and currencies supported by a given connector and payment method type combination. This will be used by frontend to set filters.

Resolution:
<think>
PR Context:
- Title: feat(payment_method): API to list countries and currencies supported by a country and payment method type
- Merged: 2024-03-28T07:15:34Z
- Files changed: 9 files
- Commits: 17 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x] 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

- [x] This PR modifies the API contract
- [ ] This PR modifies th
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(payment_method): API to list countries and currencies supported by a country and payment method
Files to modify:


**crates/api_models/src/events/payment.rs**
  Add:
    - impl: impl ApiEventMetric for ListCountriesCurrenciesRequest
    - impl: impl ApiEventMetric for ListCountriesCurrenciesResponse

**crates/api_models/src/payment_methods.rs**
  Add:
    - struct: pub::ListCountriesCurrenciesRequest
    - struct: pub::ListCountriesCurrenciesResponse
    - struct: pub::CountryCodeWithName

**crates/common_enums/src/enums.rs**
  Modify existing code

**crates/router/src/core/payment_methods/cards.rs**
  Add:
    - function: pub::list_countries_currencies_for_connector_payment_method
    - function: pub::list_countries_currencies_for_connector_payment_method_util

**crates/router/src/routes/app.rs**
  Modify existing code

**crates/router/src/routes/lock_utils.rs**
  Modify existing code

**crates/router/src/routes/payment_methods.rs**
  Add:
    - function: pub::list_countries_currencies_for_connector_payment_method

**crates/router/src/types/api/payment_methods.rs**
  Modify existing code

**crates/router_env/src/logger/types.rs**
  Modify existing code