Move Q003 to AST checker (#10923)

## Summary

This PR moves the `Q003` rule to AST checker.

This is the final rule that used the docstring detection state machine
and thus this PR removes it as well.

resolves: #7595 
resolves: #7808 

## Test Plan

- [x] `cargo test`
- [x] Make sure there are no changes in the ecosystem

crates/ruff_linter/src/lib.rs

@@ -24,7 +24,6 @@ mod docstrings;
 mod fix;
 pub mod fs;
 mod importer;
-mod lex;
 pub mod line_width;
 pub mod linter;
 pub mod logging;