Issue:
feat(verify): add new types for validate API

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates

## Description
This part of series of PR's which are aimed at adding ValidateAPI in the core. This PR specifically deals with introducing new types for the Flows and Operations which are to be added going further.
<!-- Describe your changes in detail -->


### Additional Changes

- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!-- 
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
2. Introduce the Flow and Connector Integration
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(single_use): add extra fields in `Mandate` table and `MandateData` [Blocked on #61]
- Merged: 2022-12-09T11:48:13Z
- Files changed: 9 files
- Commits: 30 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 adds single use mandate support and a 2 new fields to the mandate table (i.e. singe_use_amount, single_use_currency)
<!-- Describe your changes in detail -->


### Additional Changes

- [x] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!-
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(single_use): add extra fields in `Mandate` table and `MandateData` [Blocked on #61] (#66)
Files to modify:


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

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

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

**crates/router/src/routes/payments.rs**
  Remove:
    - function: pub::validate_pm

**crates/router/src/schema.rs**
  Modify existing code

**crates/router/src/types/api/payments.rs**
  Add:
    - enum: pub::MandateType

**crates/router/src/types/storage/mandate.rs**
  Add:
    - struct: pub::SingleUseMandate