primitives: limit Uint to int conversions

[tcoratger]

🗒️ Description

• I've removed the as_int() method for Uint because it is useless, we can directly use int() which is more Pythonic.
• I've added indexing capabilities for Uint to avoid as much as possible to convert Uint to int until this is absolutely needed.

🔗 Related Issues or PRs

✅ Checklist

• Ran tox checks to avoid unnecessary CI fails:

  uvx tox

• Considered adding appropriate tests for the changes.
• Considered updating the online docs in the ./docs/ directory.

[varun-doshi]

lgtm