refactor: cleaning, requests and split db files (#75)

Co-authored-by: shashank_attarde <shashank.attarde@juspay.in>
Co-authored-by: Arun Raj M <jarnura47@gmail.com>
Files to modify:


**db.rs**
  Modify existing code

**address.rs**
  Modify existing code

**configs.rs**
  Modify existing code

**connector_response.rs**
  Modify existing code

**customers.rs**
  Modify existing code

**events.rs**
  Modify existing code

**locker_mock_up.rs**
  Modify existing code

**mandate.rs**
  Modify existing code

**merchant_account.rs**
  Modify existing code

**merchant_connector_account.rs**
  Modify existing code

**payment_attempt.rs**
  Modify existing code

**payment_intent.rs**
  Modify existing code

**payment_method.rs**
  Modify existing code

**process_tracker.rs**
  Modify existing code

**queue.rs**
  Modify existing code

**refund.rs**
  Modify existing code

**temp_card.rs**
  Modify existing code

**app.rs**
  Modify existing code

**payment_attempt.rs**
  Modify existing code

**aci.rs**
  Modify existing code

**authorizedotnet.rs**
  Modify existing code

**checkout.rs**
  Modify existing code

**payments.rs**
  Modify existing code

**payments2.rs**
  Modify existing code

**customers.rs**
  Modify existing code

**merchant_account.rs**
  Modify existing code

**merchant_connector_account.rs**
  Modify existing code

**payment_attempt.rs**
  Modify existing code

**payment_intent.rs**
  Modify existing code

**temp_card.rs**
  Modify existing code