Introduce ExceptionCollector Interface for Cross-Framework Exception Collection

[YongGoose]

Overview

This PR introduces ExceptionCollector, a unified interface for collecting exceptions across testing frameworks (JUnit / TestNG / AssertJ / Mockito / etc). It enables soft assertions and centralized failure reporting while maintaining framework interoperability.

Key Features

• Provides a standard way to collect multiple exceptions during test execution and report them together at the end.
• Supports integration with various frameworks using an adapter pattern via the adapt() method.
• Offers methods like checkThat() and checkSucceeds() for soft assertion and safe execution.

Example Usage

// Unified exception collection  
ExceptionCollector collector = new DefaultExceptionCollector();  

// Cross-framework assertions  
collector.adapt(JUnitAdapter.class).assertEqual(actual, expected);  
collector.adapt(AssertJAdapter.class).assertThat(list).isEmpty();  

// Final failure report  
collector.reportCollectedExceptions(); // Throws MultipleFailuresError  

resolves #3