Code quality/project standards alignment

[woodruffw]

This is a meta-issue, intended to track sub-issues that will align Slither's codebase, development practices, etc. with the rest of our public tooling.

• Align README.md with our doc practices
• Streamline our installation steps
  • Move developer-specific installation instructions to their own CONTRIBUTING.md (this file already exists, but doesn't explain how to get a development environment stood up)
  • Evaluate simplifying the pip based installation (can we depend on solc directly?)
• Modernize the Python codebase
  • Switch to pyproject.toml
  • Use pypa/build for the build (sdist and wheel(s))
  • Use ruff?
• Track Python dependency upgrades via dependabot.yml
• Add some kind of QUICKSTART.md or similar guide

(This list is not intended to be exhaustive, and will be updated over time!)

[montyly]

• Is there a reason to use ruff while we already use pylint? Last time I checked, pylint has significantly more capabilities than ruff. ruff is faster, but it's not really a concern here. If we add both, we have to ensure that both can support the same ignore rules, otherwise it will create a lot of overheard for a minimal benefit.
• For the dev install, they are currently linked from the readme to the wiki - but yes we can move everything to contributing.md
• What is missing in README.md?
• Can you give more details about "Evaluate simplifying the pip based installation (can we depend on solc directly?)" ?