Issue:
db: Implement KV for Refund table

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates

## Description
<!-- Describe your changes in detail -->
Implement KV for refund table

### 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.

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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
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that will have little conversation).
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Implement Redis KV implementation for Refund table using reverse lookup.

## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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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: refactor: shrink sizes of `VARCHAR` columns and rename some columns
- Merged: 2022-12-22T06:57:59Z
- Files changed: 26 files
- Commits: 4 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates

## Description
<!-- Describe your changes in detail -->
This PR includes the following changes:

- Fixes typos in older rollback migrations.
- Shrinks sizes of database columns which previously were `VARCHAR(255)`.The general rule followed with respect to IDs has been as follows:

  - IDs generated by us or sent by merchants a
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** refactor: shrink sizes of `VARCHAR` columns and rename some columns (#188)
Files to modify:


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

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

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

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

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

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

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

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

**crates/router/src/core/refunds.rs**
  Modify existing code

**crates/router/src/core/utils.rs**
  Modify existing code

**crates/router/src/db/connector_response.rs**
  Modify existing code

**crates/router/src/db/payment_attempt.rs**
  Modify existing code

**crates/router/src/db/refund.rs**
  Modify existing code

**crates/storage_models/src/connector_response.rs**
  Modify existing code

**crates/storage_models/src/mandate.rs**
  Modify existing code

**crates/storage_models/src/payment_method.rs**
  Modify existing code

**crates/storage_models/src/query/connector_response.rs**
  Modify existing code

**crates/storage_models/src/query/payment_attempt.rs**
  Modify existing code

**crates/storage_models/src/query/refund.rs**
  Modify existing code

**crates/storage_models/src/refund.rs**
  Modify existing code

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