fix: percentage float inconsistency problem and api models changes to support surcharge feature

[hrithikesh026]

Type of Change

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

Description

Using float to deserialize the percentage was giving incorrect values. Hence changing deserializing percentage float value to
serde_json::Value and then calling to_string() on it.

Percentage object will look like this:

{
    "percentage": 2.05
}

List of changes in this PR:

• Made few fields in surcharge related structs public
• Added few more fields to SurchargeDetailsResponse (surcharge_amount, tax_on_surcharge_amount, final_amount)
• Added surcharge_details to PaymentData and populate it from payment_Attempt.surcharge_metadata.
• Added surcharge_details field to struct PaymentsSessionData and populated it from payment_data.
• Added surcharge_details field to struct PaymentsAuthorizeData and populated it from payment_data.

Additional Changes

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

Motivation and Context

How did you test it?

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