win_guest_debugging_tool: Optimize and simplify script

  The test script for the Windows guest debugging tool was
  significantly refactored to improve its structure,
  eliminate redundancy, and increase maintainability.

  Key logical improvements include:
   - The complex three-class inheritance structure was
     consolidated into a single, self-contained WinDebugToolTest
     class, simplifying the overall architecture.
   - A centralized helper method, _run_script_and_get_paths,
     was created to handle all PowerShell script executions and
     output parsing. This removes significant code duplication
     that was present in each test variant.
   - Individual test methods were streamlined to focus purely on
     their specific validation logic, delegating common tasks like
     script execution and session management to helper functions.
   - VM session management was made more robust to ensure sessions
     are properly created, reused, and cleaned up.

Signed-off-by: Dehan Meng <demeng@redhat.com>

Author: 6-dehan