Add comprehensive tox checks documentation table as reference for migration effort

[Copilot]

This PR creates a comprehensive documentation table of all tox checks currently used in the Azure SDK for Python repository. This documentation serves as a critical reference for the tox migration effort outlined in issue #42601.

What's included

The documentation provides a complete table with 27 tox environments, including:

• Check Name: The exact tox environment name
• CLI Command: The full command line syntax to run each check
• Script(s) Called: The specific Python scripts executed by each environment
• How It Works: Detailed explanation of what each check does

Key insights discovered

During the analysis, several important patterns were identified that will be crucial for the migration:

1. Common Infrastructure: Most checks rely on shared scripts like create_package_and_install.py for package building
2. Tool Versioning: Each tool is pinned to specific versions for consistency (e.g., pylint 3.2.7, mypy 1.14.1)
3. Environment Isolation: Each check uses unique proxy URLs for process isolation
4. Dependency Categories: Clear patterns emerge around base deps, packaging tools, and specialized dependencies

Check categories identified

The 27 checks fall into logical categories:

• Code Quality & Linting (6 checks): pylint, ruff, black, bandit, etc.
• Type Checking (4 checks): mypy, pyright, verifytypes variants
• Testing & Package Validation (7 checks): whl, sdist, samples, verification
• Dependency Management (4 checks): dependency compatibility testing
• Documentation & API (4 checks): sphinx, API review tools
• Utilities (2 checks): code generation and optional validations

Migration readiness

This documentation directly maps to the migration checklist in #42601, providing the detailed technical information needed to implement each check in the new dispatch_check system. Each entry includes the exact commands and scripts that need to be replicated outside of tox.

The table will serve as a living document during the migration, with checks marked as completed as they are successfully migrated to the new system.

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