Issue:
[FEATURE] Implement `MerchantKeyStoreInterface` for `MockDb`

### Feature Description

Currently the MerchantKeyStoreInterface is not implemented for MockDb. It is required for merchant account functions. And without this implementation, we cannot write tests for them.

### Possible Implementation

Checkout #172 for more details.

### Have you spent some time to check if this feature request has been raised before?

- [X] I checked and didn't find similar issue

### Have you read the Contributing Guidelines?

- [X] I have read the [Contributing Guidelines](https://github.com/juspay/hyperswitch/blob/main/docs/CONTRIBUTING.md)

### Are you willing to submit a PR?

None

Resolution:
<think>
PR Context:
- Title: test: fix failing unit tests
- Merged: 2023-07-20T10:50:21Z
- Files changed: 6 files
- Commits: 6 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
This PR includes the following changes:

- Updates the AES-GCM-256 tests to use test vectors provided by NIST for the decryption test.
- Refactors the JWE and JWS to accept payload as `impl AsRef<[u8]>` instead of `String`.
- Fixes the JWE
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** test: fix failing unit tests (#1743)
Files to modify:


**crates/common_utils/src/crypto.rs**
  Modify existing code

**crates/redis_interface/src/lib.rs**
  Modify existing code

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

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

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

**crates/router/src/services/encryption.rs**
  Add:
    - impl: impl ValueExt