Issue #2818825 by drpal, nod_, droplet, cilefen: Rename all JS files to *.es6.js and compile them

core/modules/ckeditor/js/plugins/drupalimage/plugin.es6.js

core/modules/ckeditor/js/plugins/drupalimage/plugin.js

...ules/ckeditor/js/plugins/drupalimagecaption/plugin.es6.js

.../modules/ckeditor/js/plugins/drupalimagecaption/plugin.js

core/modules/ckeditor/js/plugins/drupallink/plugin.es6.js

core/modules/ckeditor/js/plugins/drupallink/plugin.js

core/modules/ckeditor/js/views/AuralView.es6.js

core/modules/ckeditor/js/views/AuralView.js

core/modules/ckeditor/js/views/ControllerView.es6.js

core/modules/ckeditor/js/views/ControllerView.js

core/modules/ckeditor/js/views/KeyboardView.es6.js

core/modules/ckeditor/js/views/KeyboardView.js

core/modules/ckeditor/js/views/VisualView.es6.js

core/modules/ckeditor/js/views/VisualView.js

core/modules/ckeditor/tests/modules/js/ajax-css.es6.js

core/modules/ckeditor/tests/modules/js/ajax-css.js

core/modules/color/color.es6.js

core/modules/color/color.js

core/modules/color/preview.es6.js

core/modules/color/preview.js