Context

Allure-java currently lacks a component for visualizing the difference between two strings. Similar functionality is available in the allure-jsonunit module, but it is only available for json and is called only as a result of Assert, which is not always suitable for all tasks that require visualization, such as preparing test data from a template.

I propose to add a solution based on the most popular java solution for diff - https://github.com/java-diff-utils/java-diff-utils

Which will:

1. Be suitable for all text formats, not just json
2. With a simple API
3. Available for building Assert
4. With extended functionality in Attachment

Checklist

• Sign Allure CLA
• Provide unit tests