Issue:
[BUG] Internal Server Error thrown when updating or deleting non-existent API key

### Bug Description

When a user tries to update or delete a non-existent API key, an internal server error is thrown. The expected behavior is that the server returns a 404 status code, informing that the API key does not exist.

### Expected Behavior

Server should return 404 status code.

### Actual Behavior

Server returns internal server error (500 status code) with the following response:

```json
{
  "error": {
    "type": "api",
    "message": "Something went wrong",
    "code": "HE_00"
  }
}
```

### Steps To Reproduce

The following steps assume that the admin API key for the deployed server is known to the user.

1. Create a merchant account using the create merchant account API and admin API key.
2. Try to use the update API key endpoint or the delete API key endpoint with a non-existent API key ID.

For example, the delete API key request could look like so:
```shell
curl --location --request DELETE 'http://localhost:8080/api_keys/<merchant_id>/a-non-existent-key-id' \
  --header 'Content-Type: application/json' \
  --header 'Accept: application/json' \
  --header 'api-key: <ADMIN_API_KEY>'
```

Server returns the aforementioned response.


### Have you spent some time checking if this bug has been raised before?

- [X] I checked and didn't find a 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?

Yes, I am willing to submit a PR!

Resolution:
<think>
PR Context:
- Title: fix(api_keys): fix internal server error being thrown when trying to update or delete non-existent API key
- Merged: 2024-02-22T07:51:09Z
- Files changed: 1 files
- Commits: 1 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
This PR fixes a bug with the update API key and delete API key endpoints throwing an internal server error when a non-existent API key was provided.

## Motivation and Context
<!--
Why is this change required? What problem does it solve?

</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** fix(api_keys): fix internal server error being thrown when trying to update or delete non-existent A
Files to modify:


**crates/storage_impl/src/errors.rs**
  Modify existing code