feat: restructure devcontainers and improve CI #16

[d4rm5]

This pull request introduces a major restructuring of the devcontainer setup, along with significant improvements to the CI workflow and development environment.

Devcontainer Restructuring

• Multiple Devcontainer Variants: The project now supports multiple devcontainer variants within the .devcontainer directory. This allows for different development
  environments tailored to specific needs (e.g., auditor, hardened, isolated, minimal, legacy).
• Comprehensive Documentation: The README has been updated with comprehensive documentation for each devcontainer variant, explaining their purpose and included tools.

CI Workflow Enhancements

• Tiered Testing: The GitHub Actions workflow for testing the devcontainers has been updated to use a tiered approach:
  • A "Minimal Tools" test runs on all containers to verify baseline functionality (e.g., Foundry).
  • An "Auditor Tools" test runs on auditor, hardened, and isolated containers to check for specialized tools like Slither, Mythril, and Echidna.
  • An "Isolation" test runs exclusively on the isolated container to ensure its security features (read-only filesystem, no network) are active.

Python Environment Management

• asdf replaced with uv: The python version management has been migrated from asdf to uv. uv is a faster and more modern python package installer and resolver.

Other Changes

• Minor updates to the README file.