[syntax-errors] nonlocal declaration at module level (#17559)

## Summary

Part of #17412

Add a new compile-time syntax error for detecting `nonlocal`
declarations at a module level.

## Test Plan

- Added new inline tests for the syntax error
- Updated existing tests for `nonlocal` statement parsing to be inside a
function scope

Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>

crates/ruff_python_parser/resources/inline/err/nonlocal_declaration_at_module_level.py

@@ -0,0 +1,2 @@
+nonlocal x
+nonlocal x, y

crates/ruff_python_parser/resources/inline/err/nonlocal_stmt_empty.py

@@ -1 +1,2 @@
-nonlocal
+def _():
+    nonlocal

crates/ruff_python_parser/resources/inline/err/nonlocal_stmt_expression.py

@@ -1 +1,2 @@
-nonlocal x + 1
+def _():
+    nonlocal x + 1

crates/ruff_python_parser/resources/inline/err/nonlocal_stmt_trailing_comma.py

@@ -1,3 +1,4 @@
-nonlocal ,
-nonlocal x,
-nonlocal x, y,
+def _():
+    nonlocal ,
+    nonlocal x,
+    nonlocal x, y,

crates/ruff_python_parser/resources/inline/ok/nonlocal_declaration_at_module_level.py

@@ -0,0 +1,2 @@
+def _():
+    nonlocal x

crates/ruff_python_parser/resources/inline/ok/nonlocal_stmt.py

@@ -1,2 +1,3 @@
-nonlocal x
-nonlocal x, y, z
+def _():
+    nonlocal x
+    nonlocal x, y, z