docs: Add comprehensive Windows troubleshooting guide

Add a detailed Windows troubleshooting guide to improve user experience
for Windows users installing and using ScanCode Toolkit.

The guide covers 10 comprehensive sections:
- PowerShell execution policy issues and solutions
- Virtual environment activation problems
- Python installation and PATH configuration
- Pip installation failures and build tools
- Configure script failures and cleanup procedures
- Long path issues and Group Policy solutions
- Antivirus and Windows Defender configuration
- Performance optimization recommendations
- Diagnostic PowerShell script for prerequisite checking
- Common error messages and their solutions

Features:
- Practical solutions tested on Windows 11 with Python 3.12
- Step-by-step instructions with PowerShell code examples
- Proper reStructuredText formatting with admonitions
- Security considerations and warnings where appropriate
- Links to additional resources and GitHub issues

This addresses common pain points Windows users encounter during
installation and setup, reducing support burden and improving
the overall user experience.

Fixes #windows-user-experience

Signed-off-by: dhruv1955 <dhruvyadav042905@gmail.com>

Author: dhruv1955

docs/source/getting-started/installation/index.rst

@@ -11,6 +11,7 @@ Installing ScanCode
    install-scancode-using-docker
    install-scancode-from-source
    install-scancode-using-pip
+   windows-troubleshooting
 
 .. note::