Add NoSmartQuotes lint to reject smart quotes in EIPs

[sumitvekariya]

Description

This PR implements a new lint rule to reject smart quotes in EIPs, resolving issue #129.

Smart quotes (", ", ', ') can be problematic in EIPs, especially in code blocks where they can cause syntax errors. This new lint detects these characters and suggests replacing them with straight quotes (", ').

Changes:

1. Created a new lint implementation NoSmartQuotes that detects Unicode smart quotes in markdown content
2. Added tests to verify the lint correctly identifies smart quotes in text, code blocks, and other contexts
3. The lint ignores straight quotes and only flags actual smart quotes

Files changed:

• Added eipw-lint/src/lints/markdown/no_smart_quotes.rs - Implements the lint rule
• Added eipw-lint/tests/lint_markdown_no_smart_quotes.rs - Tests for the new lint
• Modified eipw-lint/src/lints/markdown.rs - Registered the new lint module
• Modified eipw-lint/src/lints/known_lints.rs - Added the new lint to the DefaultLint enum

Fixes #129