language: Remove inline menus

Inline menus didn't work anyway--menus have to be referenced by ID
(though, curiously, you *can* put the <menu> within the <property> tag
and immediately reference it--but that's a hack, and not what
blueprint-compiler was doing).

tests/sample_errors/assign_inline_menu.blp

@@ -1,5 +0,0 @@
-using Gtk 4.0;
-
-Button {
-  label: menu {};
-}

tests/sample_errors/assign_inline_menu.err

@@ -1 +0,0 @@
-4,3,15,Cannot assign Gio.Menu to string

tests/sample_errors/inline_menu.err

@@ -0,0 +1 @@
+4,15,4,Namespace Gtk does not contain a type called menu

tests/samples/inline_menu.ui

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<interface>
-  <requires lib="gtk" version="4.0"/>
-  <object class="GtkMenuButton">
-    <property name="menu-model">
-      <menu id="primary_menu"></menu>
-    </property>
-  </object>
-</interface>

tests/test_samples.py

@@ -140,7 +140,6 @@ class TestSamples(unittest.TestCase):
         self.assert_sample("file_filter")
         self.assert_sample("flags")
         self.assert_sample("id_prop")
-        self.assert_sample("inline_menu")
         self.assert_sample("layout")
         self.assert_sample("menu")
         self.assert_sample("numbers")
@@ -167,7 +166,6 @@ class TestSamples(unittest.TestCase):
         self.assert_sample_error("a11y_prop_obj_dne")
         self.assert_sample_error("a11y_prop_type")
         self.assert_sample_error("abstract_class")
-        self.assert_sample_error("assign_inline_menu")
         self.assert_sample_error("action_widget_float_response")
         self.assert_sample_error("action_widget_have_no_id")
         self.assert_sample_error("action_widget_multiple_default")
@@ -188,6 +186,7 @@ class TestSamples(unittest.TestCase):
         self.assert_sample_error("filters_in_non_file_filter")
         self.assert_sample_error("gtk_3")
         self.assert_sample_error("gtk_exact_version")
+        self.assert_sample_error("inline_menu")
         self.assert_sample_error("invalid_bool")
         self.assert_sample_error("layout_in_non_widget")
         self.assert_sample_error("no_import_version")