make globalLookups a module to extend, not a stub

refs FOO-2498
flag=none
[pin-commit-multiple_root_accounts=5bd07698db01843f784622d0a99277bbd7be0dc1]

the stub pattern won't work with zeitwerk

TEST PLAN:
  1) specs pass with plugins migrated to autoextension of GL

Change-Id: I29c7249e38d06e54d4fc111f8a845d4e94ea70f3
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/276301
Reviewed-by: Jacob Burroughs <jburroughs@instructure.com>
Tested-by: Ethan Vizitei <evizitei@instructure.com>
QA-Review: Ethan Vizitei <evizitei@instructure.com>
Product-Review: Ethan Vizitei <evizitei@instructure.com>

lib/global_lookups.rb

@@ -18,17 +18,11 @@
 # with this program. If not, see <http://www.gnu.org/licenses/>.
 
 module GlobalLookups
-  unless singleton_class.method_defined?(:enabled?)
-    def self.enabled?
-      false
-    end
-  end
-
-  module DevUtils
-    unless singleton_class.method_defined?(:initialize_ddb_for_development!)
-      def self.initialize_ddb_for_development!
-        puts("Nothing to do for global lookups stub")
-      end
-    end
+  # this is a bit convoluted, but it makes it simpler
+  # to have a module-level interface like this that
+  # can be overidden easily in plugins by having
+  # modules prepend themselves to override what "Config" does.
+  def self.enabled?
+    GlobalLookups::Config.new.enabled?
   end
 end

lib/global_lookups/config.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+#
+# Copyright (C) 2021 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+module GlobalLookups
+  # This class is just a stub for overriding in
+  # plugins in cases where that's useful.
+  class Config
+    def enabled?
+      false
+    end
+  end
+end

lib/global_lookups/dev_utils.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+#
+# Copyright (C) 2021 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+module GlobalLookups
+  class DevUtils
+    # this is a bit convoluted, but it makes it simpler
+    # to have a module-level interface like this that
+    # can be overidden easily in plugins by having
+    # modules prepend themselves to override what "DevUtils" does.
+    def initialize_ddb_for_development!(recreate: false)
+      puts("Nothing to do for global lookups stub")
+    end
+
+    def self.initialize_ddb_for_development!(recreate: false)
+      GlobalLookups::DevUtils.new.initialize_ddb_for_development!(recreate: recreate)
+    end
+  end
+end