Part of WOOMOB-935

Description

Refactored FormattableAmountTextField to replace the hardcoded font override with a more flexible Style struct that allows dependency injection of fonts, since .posHeadingRegular won't be available once POS is in a separate module. As the refactoring affects multiple use cases in the app, I made these changes in one PR.

Changes made:

• Replaced Style enum with a Style struct containing showsBorder, textAlignment, and optional font properties
• Updated POSFormattableAmountTextFieldAdaptor to accept and pass font parameter from POS module
• Modified POSExternalViewProviding protocol to include font parameter in createFormattableAmountTextField method
• Updated POS integration to pass the appropriate font based on dynamic type size

This refactoring maintains the same behavior while improving modularity and allowing better font customization for different use cases.

Steps to reproduce

1. Open POS cash collection view
2. Verify the amount text field displays with the correct POS font styling
3. Test other uses of FormattableAmountTextField (order creation, payment methods, shipping) to ensure they continue working as before
4. Test with different dynamic type sizes to ensure font scaling works correctly

Testing information

Regression testing:

• POS cash collection view displays amount field with correct font
• Order creation custom amount entry works normally
• Cash payment tender view functions properly
• Order creation shipping amount entry works normally

Screenshots

I compared the following screens from PR branch & trunk:

POS cash view:

Order creation add custom amount:

custom amount	custom amount filled	custom percentage

Order creation shipping line:

Order cash payment:

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.