get rid of global notify (#5355)

* [toasts] get rid of notify globals, refactor messageToasts for use by entire app

* [remove notify] use arrow func in ajax call

* fix lint + tests

* actually fix tests from messageToast refactor

* add 'test:one' npm script

* debugger

* [toasts] convert bootstrap flash messages to toasts in explore + sqllab

* [toasts][tests] import from right file

superset/assets/spec/javascripts/sqllab/SqlEditorLeftBar_spec.jsx

@@ -20,6 +20,7 @@ describe('SqlEditorLeftBar', () => {
       queryEditorSetDb: sinon.stub(),
       setDatabases: sinon.stub(),
       addTable: sinon.stub(),
+      addDangerToast: sinon.stub(),
     },
     tables: [table],
     queryEditor: defaultQueryEditor,