Issue:
refactor(connector): added amount conversion to FISERV

## 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 -->
added MinorUnit for amount conversion

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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If it fixes an open issue, please link to the issue here.

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fixes #5947 

## How did you test it?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Resolution:
<think>
PR Context:
- Title: refactor(connector): [FISERV, HELCIM] Add amount conversion framework to Fiserv, Helcim
- Merged: 2025-03-12T07:58:54Z
- Files changed: 8 files
- Commits: 13 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 -->
added **FloatMajorUnit** for amount conversion for **Fiserv**
added **FloatMajorUnit** for amount conversion for **Helcim**

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ 
</think>

To implement this, you'll need to modify:


**Detailed Implementation:**


**Commit 1:** refactor(connector): [FISERV, HELCIM] Add amount conversion framework to Fiserv, Helcim (#7336)
Co-a
Files to modify:


**crates/hyperswitch_connectors/src/connectors/fiserv.rs**
  Remove:
    - struct: pub::Fiserv
  Add:
    - function: pub::new
    - struct: pub::Fiserv

**crates/hyperswitch_connectors/src/connectors/fiserv/transformers.rs**
  Modify existing code

**crates/hyperswitch_connectors/src/connectors/helcim.rs**
  Remove:
    - struct: pub::Helcim
  Add:
    - function: pub::new
    - struct: pub::Helcim
    - impl: impl Helcim

**crates/hyperswitch_connectors/src/connectors/helcim/transformers.rs**
  Modify existing code

**crates/hyperswitch_connectors/src/utils.rs**
  Remove:
    - function: pub::str_to_f32

**crates/router/src/types/api.rs**
  Modify existing code

**crates/router/tests/connectors/fiserv.rs**
  Modify existing code

**crates/router/tests/connectors/helcim.rs**
  Modify existing code