fix(dispute): change dispute currency type to currency enum (#6454)

Co-authored-by: hyperswitch-bot[bot] <148525504+hyperswitch-bot[bot]@users.noreply.github.com>
Files to modify:


**disputes.rs**
  Modify existing code

**dispute.rs**
  Modify existing code

**schema.rs**
  Modify existing code

**schema_v2.rs**
  Modify existing code

**transformers.rs**
  Modify existing code

**novalnet.rs**
  Modify existing code

**disputes.rs**
  Modify existing code

**webhooks.rs**
  Modify existing code

**adyen.rs**
  Modify existing code

**bluesnap.rs**
  Modify existing code

**braintree.rs**
  Modify existing code

**transformers.rs**
  Modify existing code

**transformers.rs**
  Modify existing code

**payme.rs**
  Modify existing code

**paypal.rs**
  Modify existing code

**rapyd.rs**
  Modify existing code

**transformers.rs**
  Modify existing code

**transformers.rs**
  Modify existing code

**utils.rs**
  Add:
    - function: pub::convert_uppercase

**incoming.rs**
  Modify existing code

**dispute.rs**
  Modify existing code

**dispute.rs**
  Modify existing code

**dispute_event.rs**
  Modify existing code

**dispute.rs**
  Modify existing code

**transformers.rs**
  Modify existing code

**sample_data.rs**
  Modify existing code