[syntax-errors] Reimplement PLE0118 (#17135)

Summary
--

This PR reimplements
[load-before-global-declaration
(PLE0118)](https://docs.astral.sh/ruff/rules/load-before-global-declaration/)
as a semantic syntax error.

I added a `global` method to the `SemanticSyntaxContext` trait to make
this very easy, at least in ruff. Does red-knot have something similar?

If this approach will also work in red-knot, I think some of the other
PLE rules are also compile-time errors in CPython, PLE0117 in
particular. 0115 and 0116 also mention `SyntaxError`s in their docs, but
I haven't confirmed them in the REPL yet.

Test Plan
--

Existing linter tests for PLE0118. I think this actually can't be tested
very easily in an inline test because the `TestContext` doesn't have a
real way to track globals.

---------

Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff_python_parser/tests/fixtures.rs

@@ -488,4 +488,8 @@ impl SemanticSyntaxContext for TestContext {
     fn report_semantic_error(&self, error: SemanticSyntaxError) {
         self.diagnostics.borrow_mut().push(error);
     }
+
+    fn global(&self, _name: &str) -> Option<TextRange> {
+        None
+    }
 }