Add TAPI utility helpers for PredefinedContent and SaleToAcquirerData

[gcatanese]

Summary

Introduces hand-written utility helpers in com.adyen.util.tapi to work with fields from the auto-generated TAPI models that require additional parsing logic:

• PredefinedContent.ReferenceID string with URL query string format
• SaleData.SaleToAcquirerData string with either JSON or key-value pairs

New classes

PredefinedContentHelper
Parses the PredefinedContent.ReferenceID URL query string into typed accessors: getEvent(), getTransactionId(), getTimeStamp(), and get(key).

SaleToAcquirerData
A Jackson-based POJO representing the decoded acquirer data. Supports both formats described in the Adyen docs:

• Base64-encoded JSON (fromBase64)
• Form-encoded key-value pairs (fromKeyValuePairs)

SaleDataHelper
Wraps a tapi.SaleData instance and exposes getSaleToAcquirerData(), auto-detecting the format of the underlying string.

Notes

• All helpers live outside com.adyen.model.tapi which is auto-generated from the OpenAPI spec
• No dependency on the legacy com.adyen.model.terminal package
• Uses java.util.Base64 and Jackson throughout, consistent with the rest of the TAPI stack

[gemini-code-assist]

Code Review

This pull request introduces several helper classes—PredefinedContentHelper, SaleDataHelper, and SaleToAcquirerData—to handle the parsing of terminal API data, including URL query-like strings and SaleToAcquirerData in both Base64-encoded JSON and form-encoded formats. The review feedback highlights an opportunity to improve efficiency by avoiding redundant Base64 decoding in SaleDataHelper and suggests explicitly defining the UTF-8 charset when converting bytes to strings in SaleToAcquirerData for better environment consistency.