PY-35627 Make Python formatter always add a line break after a decorator list

For regular non-async functions, it already worked thanks to PyTokenSeparatorGenerator.

GitOrigin-RevId: b60dba7b34710cad7dc46ad6f943b3944fc00c42

python/python-psi-impl/src/com/jetbrains/python/formatter/PythonFormattingModelBuilder.java

@@ -122,7 +122,7 @@ public class PythonFormattingModelBuilder implements FormattingModelBuilder, Cus
       .before(PATTERN_ARGUMENT_LIST).spaceIf(commonSettings.SPACE_BEFORE_METHOD_CALL_PARENTHESES)
 
       .around(DECORATOR_CALL).spacing(1, Integer.MAX_VALUE, 0, true, 0)
-      .after(DECORATOR_LIST).spacing(1, Integer.MAX_VALUE, 0, true, 0)
+      .after(DECORATOR_LIST).spacing(1, Integer.MAX_VALUE, 1, true, 0)
 
       .aroundInside(EQ, ASSIGNMENT_STATEMENT).spaceIf(commonSettings.SPACE_AROUND_ASSIGNMENT_OPERATORS)
       .aroundInside(EQ, TYPE_ALIAS_STATEMENT).spaceIf(commonSettings.SPACE_AROUND_ASSIGNMENT_OPERATORS)

python/testData/quickFixes/PyMakeMethodStaticQuickFixTest/asyncMethod.py

@@ -0,0 +1,3 @@
+class C:
+    async def <caret>m(self, p):
+        return f'{p}'

python/testData/quickFixes/PyMakeMethodStaticQuickFixTest/asyncMethod_after.py

@@ -0,0 +1,4 @@
+class C:
+    @staticmethod
+    async def <caret>m(p):
+        return f'{p}'

python/testSrc/com/jetbrains/python/quickFixes/PyMakeMethodStaticQuickFixTest.java

@@ -45,4 +45,8 @@ public class PyMakeMethodStaticQuickFixTest extends PyQuickFixTestCase {
     doMultifilesTest(PyMethodMayBeStaticInspection.class, PyPsiBundle.message("QFIX.NAME.make.static"), new String[]{"test.py"});
   }
 
+  // PY-35627
+  public void testAsyncMethod() {
+    doQuickFixTest(PyMethodMayBeStaticInspection.class, PyPsiBundle.message("QFIX.NAME.make.static"));
+  }
 }