refactor: move xmodule folder to root

- Moving xmodule folder to root as we're dissolving sub-projects of common folder in edx-platform
    - More info: https://openedx.atlassian.net/browse/BOM-2579
- -e common/lib/xmodule has been removed from the requirements as xmodule has itself become the part of edx-platform and not being installed through requirements
- The test files common/lib/xmodule/test_files/ have been removed as they are not being used anymore

xmodule/js/spec/html/edit_spec.js

@@ -0,0 +1,66 @@
+describe('HTMLEditingDescriptor', function() {
+  beforeEach(() => window.baseUrl = "/static/deadbeef/");
+  afterEach(() => delete window.baseUrl);
+  describe('Visual HTML Editor', function() {
+    beforeEach(function() {
+      loadFixtures('html-edit-visual.html');
+      this.descriptor = new HTMLEditingDescriptor($('.test-component'));
+    });
+    it('Returns data from Visual Editor if text has changed', function() {
+      const visualEditorStub =
+        {getContent() { return 'from visual editor'; }};
+      spyOn(this.descriptor, 'getVisualEditor').and.callFake(() => visualEditorStub);
+      const { data } = this.descriptor.save();
+      expect(data).toEqual('from visual editor');
+    });
+    it('Returns data from Raw Editor if text has not changed', function() {
+      const visualEditorStub =
+        {getContent() { return '<p>original visual text</p>'; }};
+      spyOn(this.descriptor, 'getVisualEditor').and.callFake(() => visualEditorStub);
+      const { data } = this.descriptor.save();
+      expect(data).toEqual('raw text');
+    });
+    it('Performs link rewriting for static assets when saving', function() {
+      const visualEditorStub =
+        {getContent() { return 'from visual editor with /c4x/foo/bar/asset/image.jpg'; }};
+      spyOn(this.descriptor, 'getVisualEditor').and.callFake(() => visualEditorStub);
+      const { data } = this.descriptor.save();
+      expect(data).toEqual('from visual editor with /static/image.jpg');
+    });
+    it('When showing visual editor links are rewritten to c4x format', function() {
+      const visualEditorStub = {
+        content: 'text /static/image.jpg',
+        startContent: 'text /static/image.jpg',
+        focus() {},
+        setContent(x) { this.content = x; },
+        getContent() { return this.content; }
+      };
+
+      this.descriptor.initInstanceCallback(visualEditorStub);
+      expect(visualEditorStub.getContent()).toEqual('text /c4x/foo/bar/asset/image.jpg');
+    });
+    it('Enables spellcheck', () => expect($('.html-editor iframe')[0].contentDocument.body.spellcheck).toBe(true));
+    it('Retains ascii characters', function() {
+      const editorData = '<a href="/static/Programación_Gas.pptx">fóó</a>';
+      const expectedData = '<p><a href="/static/Programación_Gas.pptx">fóó</a></p>'
+
+      this.descriptor.getVisualEditor().setContent(editorData)
+      const savedContent = this.descriptor.getVisualEditor().getContent()
+      expect(savedContent).toEqual(expectedData);
+    });
+    it('Editor base URL does not contain double slash', function(){
+      const editor = this.descriptor.getVisualEditor();
+      expect(editor.editorManager.baseURL).not.toContain('//');
+    });
+  });
+  describe('Raw HTML Editor', function() {
+    beforeEach(function() {
+      loadFixtures('html-editor-raw.html');
+      this.descriptor = new HTMLEditingDescriptor($('.test-component'));
+    });
+    it('Returns data from raw editor', function() {
+      const { data } = this.descriptor.save();
+      expect(data).toEqual('raw text');
+    });
+  });
+});