refactor(connector): [Paypal]Enhance currency Mapping with ConnectorCurrencyCommon Trait

[srujanchikke]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

Problem : Currently, amount mapping for different connectors are handled by hard coding dollars/cents which has been leading to multiple bugs due to incorrect mapping. Need to handle this better in code by having separate types for dollar vs cents .

Solution : To address this issue and improve code maintainability, this pull request introduces the get_currecny_unit from ConnectorCommon trait. This function allows connectors to declare their accepted currency unit as either "Base" or "Minor" .

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

Implement the ConnectorCurrencyCommon trait, where you can declare the accepted currency unit (either Base or Minor) using the get_currency_unit method in ConnectorCommon trait .

How did you test it?

tested it locally

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible
• I added a CHANGELOG entry if applicable

[prasunna09]

Can you please test for one zero decimal currency, two-decimal, and three-decimal, and confirm whether it is working as expected?

[srujanchikke]

Can you please test for one zero decimal currency, two-decimal, and three-decimal, and confirm whether it is working as expected?
tested with both USD and JPY