Added normalize-path-separator option as debugging .NET on Windows 10 with netcoredbg was not registering breakpoints

Add normalize-path-separator option for path separator normalization Some debug adapters require exact path matching with symbol files that may use different path separators than Emacs. This is particularly important for netcoredbg on Windows, where PDB files contain backslash separators but Emacs uses forward slashes. The new normalize-path-separator configuration option allows users to specify path separator normalization: - 'windows: Convert forward slashes to backslashes - 'unix: Convert backslashes to forward slashes - nil (default): No normalization This ensures breakpoints can be properly verified by debug adapters that perform strict path matching. Fixes: Issue where netcoredbg on Windows fails to verify breakpoints due to path separator mismatch between Emacs (/) and PDB symbols (\).