Issue:
feat(stripe): add setup intent in connector integration (stripe)

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates

## Description
This PR adds a stripe POC for the verify API
<!-- Describe your changes in detail -->


### Additional Changes

- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
Here, the intension is adding a new Validation feature in PaymentsCore, for that reason following are the steps that the change is broken down to.

1. Create new types for the change #45 
2. Introduce the Flow and Connector Integration #47 
3. Add Stripe POC
4. Move the mandate related behaviour to domain
5. Introduce the new operation and all the related components in the payments core
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## How did you test it?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Resolution:
<think>
PR Context:
- Title: feat(payment_method_validate): add new operation to payments_operation_core for payment method validation
- Merged: 2022-12-07T11:53:06Z
- Files changed: 7 files
- Commits: 12 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates

## Description
This PR creates a new operation and links it to the payments core and verify flow, creates supporting trackers and domain implementation.
<!-- Describe your changes in detail -->


### Additional Changes

- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment var
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(payment_method_validate): add new operation to payments_operation_core for payment method valid
Files to modify:


**crates/router/src/connector/braintree.rs**
  Modify existing code

**crates/router/src/core/payments/helpers.rs**
  Modify existing code

**crates/router/src/core/payments/operations.rs**
  Add:
    - mod: private::payment_method_validate

**crates/router/src/core/payments/operations/payment_create.rs**
  Modify existing code

**crates/router/src/core/payments/operations/payment_method_validate.rs**
  Add:
    - function: private::validate_request
    - function: private::get_trackers
    - function: private::update_trackers
    - function: private::get_or_create_customer_details
    - function: private::make_pm_data
    - function: private::make_payment_attempt
    - function: private::make_payment_intent
    - struct: pub::PaymentMethodValidate
    - impl: impl ValidateRequest<F, api::VerifyRequest> for PaymentMethodValidate
    - impl: impl GetTracker<F, PaymentData<F>, api::VerifyRequest> for PaymentMethodValidate
    - impl: impl UpdateTracker<F, PaymentData<F>, api::VerifyRequest> for PaymentMethodValidate
    - impl: impl Domain<F, api::VerifyRequest> for Op
    - impl: impl PaymentMethodValidate

**crates/router/src/types/api/payments.rs**
  Add:
    - function: pub::is_mandate
    - function: private::from
    - function: private::from
    - struct: pub::MandateValidationFields
    - impl: impl MandateValidationFields
    - impl: impl From<&PaymentsRequest> for MandateValidationFields
    - impl: impl From<&VerifyRequest> for MandateValidationFields

**crates/router_derive/src/macros/operation.rs**
  Modify existing code