Use `semantic().global()` to power `global-statement` rule (#5795)

## Summary

The intent of this rule is to always flag the `global` declaration, not
the usage. The current implementation does the wrong thing if a global
is assigned multiple times. Using `semantic().global()` is also more
efficient.

crates/ruff/resources/test/fixtures/pylint/global_statement.py

@@ -80,3 +80,8 @@ def multiple_assignment():
     global CONSTANT  # [global-statement]
     CONSTANT = 1
     CONSTANT = 2
+
+
+def no_assignment():
+    """Shouldn't warn"""
+    global CONSTANT

crates/ruff/src/rules/pylint/rules/global_statement.rs

@@ -1,5 +1,3 @@
-use rustpython_parser::ast::Ranged;
-
 use ruff_diagnostics::{Diagnostic, Violation};
 use ruff_macros::{derive_message_formats, violation};
 
@@ -55,21 +53,14 @@ impl Violation for GlobalStatement {
 
 /// PLW0603
 pub(crate) fn global_statement(checker: &mut Checker, name: &str) {
-    let scope = checker.semantic().scope();
-    if let Some(binding_id) = scope.get(name) {
-        let binding = checker.semantic().binding(binding_id);
-        if binding.is_global() {
-            if let Some(source) = binding.source {
-                let source = checker.semantic().stmts[source];
+    if let Some(range) = checker.semantic().global(name) {
         checker.diagnostics.push(Diagnostic::new(
             GlobalStatement {
                 name: name.to_string(),
             },
             // Match Pylint's behavior by reporting on the `global` statement`, rather
             // than the variable usage.
-                    source.range(),
+            range,
         ));
     }
-        }
-    }
 }

crates/ruff/src/rules/pylint/snapshots/ruff__rules__pylint__tests__PLW0603_global_statement.py.snap

@@ -89,12 +89,13 @@ global_statement.py:80:5: PLW0603 Using the global statement to update `CONSTANT
 82 |     CONSTANT = 2
    |
 
-global_statement.py:81:5: PLW0603 Using the global statement to update `CONSTANT` is discouraged
+global_statement.py:80:5: PLW0603 Using the global statement to update `CONSTANT` is discouraged
    |
+78 | def multiple_assignment():
 79 |     """Should warn on every assignment."""
 80 |     global CONSTANT  # [global-statement]
+   |     ^^^^^^^^^^^^^^^ PLW0603
 81 |     CONSTANT = 1
-   |     ^^^^^^^^^^^^ PLW0603
 82 |     CONSTANT = 2
    |