Add comprehensive L2 bootstrap initialization test suite

[Vismalskumar0]

• Add test_bootstrap_initialization.py: 23 comprehensive test cases covering complete bootstrap flow
• Add bootstrap_test_config.py: Centralized configuration for bootstrap testing
• Add tr69hostif_bootstrap_initialization.feature: BDD scenarios for bootstrap validation
• Add run_bootstrap_tests.sh: Automated test runner with environment setup and reporting
• Add Makefile.bootstrap: Multiple test targets for different use cases
• Update run_l2.sh: Integrate bootstrap tests as first test suite

Test Coverage:

• Process startup and command line processing
• Signal handler setup and thread management
• Configuration manager initialization
• RFC/Legacy mode detection and setup
• IARM bus communication setup
• Data model merging and loading
• Server threads (JSON, HTTP, Update Handler)
• WebPA/Parodus integration
• RBUS interface setup
• Bootstrap/RFC stores initialization
• SystemD notification and service ready
• Main event loop and process stability
• Performance monitoring and functional verification

Features:

• Health scoring with 70% minimum threshold
• Error detection for 12+ critical conditions
• Success validation for 15+ indicators
• Configuration file validation
• Process stability monitoring
• Comprehensive reporting (JSON, HTML)
• Multiple execution modes (quick, verbose, performance)