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

Spin out from https://github.com/juspay/hyperswitch/issues/172. Please refer to that issue for more information.

Resolution:
<think>
PR Context:
- Title: feat(db): Implement `ReverseLookupInterface` for `MockDb`
- Merged: 2023-09-12T09:53:45Z
- Files changed: 4 files
- Commits: 4 commits

Implementation approach:
Implement the missing implementation of `MockDb` for `ReverseLookup`

Closes #1115

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [x] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->


### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application confi
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** feat(db): Implement `ReverseLookupInterface` for `MockDb` (#2119)
Files to modify:


**crates/diesel_models/src/reverse_lookup.rs**
  Add:
    - function: private::from
    - impl: impl From<ReverseLookupNew> for ReverseLookup

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

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