[flake8-use-pathlib] Dotless suffix passed to Path.with_suffix() (PTH901) (#14779)

## Summary

Resolves #14441.

## Test Plan

`cargo nextest run` and `cargo insta test`.

crates/ruff_python_semantic/src/analyze/typing.rs

@@ -741,6 +741,43 @@ impl TypeChecker for IoBaseChecker {
     }
 }
 
+pub struct PathlibPathChecker;
+
+impl PathlibPathChecker {
+    fn is_pathlib_path_constructor(semantic: &SemanticModel, expr: &Expr) -> bool {
+        let Some(qualified_name) = semantic.resolve_qualified_name(expr) else {
+            return false;
+        };
+
+        matches!(
+            qualified_name.segments(),
+            [
+                "pathlib",
+                "Path"
+                    | "PosixPath"
+                    | "PurePath"
+                    | "PurePosixPath"
+                    | "PureWindowsPath"
+                    | "WindowsPath"
+            ]
+        )
+    }
+}
+
+impl TypeChecker for PathlibPathChecker {
+    fn match_annotation(annotation: &Expr, semantic: &SemanticModel) -> bool {
+        Self::is_pathlib_path_constructor(semantic, annotation)
+    }
+
+    fn match_initializer(initializer: &Expr, semantic: &SemanticModel) -> bool {
+        let Expr::Call(ast::ExprCall { func, .. }) = initializer else {
+            return false;
+        };
+
+        Self::is_pathlib_path_constructor(semantic, func)
+    }
+}
+
 /// Test whether the given binding can be considered a list.
 ///
 /// For this, we check what value might be associated with it through it's initialization and
@@ -824,6 +861,12 @@ pub fn is_io_base_expr(expr: &Expr, semantic: &SemanticModel) -> bool {
     IoBaseChecker::match_initializer(expr, semantic)
 }
 
+/// Test whether the given binding can be considered a `pathlib.PurePath`
+/// or an instance of a subclass thereof.
+pub fn is_pathlib_path(binding: &Binding, semantic: &SemanticModel) -> bool {
+    check_type::<PathlibPathChecker>(binding, semantic)
+}
+
 /// Find the [`ParameterWithDefault`] corresponding to the given [`Binding`].
 #[inline]
 fn find_parameter<'a>(