Added error, loading modal and popover components

• Added:
- error, loading modal components
- error, loading popover components

• Removed:
- ModalLoading from async_components

• Updated:
- ModalRoot to use new components

app/javascript/gabsocial/components/modal/loading_modal.js

@@ -0,0 +1,22 @@
+import Block from '../block'
+import ColumnIndicator from '../column_indicator'
+
+export default class LoadingModal extends PureComponent {
+
+  render() {
+    return (
+      <div className={_s.width330PX}>
+        <Block>
+          <div className={[_s.default, _s.px15, _s.py15, _s.mt15, _s.mb15].join(' ')}>
+            <div className={[_s.default, _s.px15, _s.py15, _s.mt15, _s.mb15, _s.alignItemsCenter, _s.justifyContentCenter].join(' ')}>
+
+              <ColumnIndicator type='loading' />
+
+            </div>
+          </div>
+        </Block>
+      </div>
+    )
+  }
+
+}