Fix uses of loading spinner (#2797)

* Update Loading Indicator

- Fix mistake in LoadingIndicator Less
- Middle align the loading indicator when inline
- Fix Loading Indicator not correctly accepting container class names
- Add inline and block attributes

* Fix loading indicator in composer

* Fix loading indicator on notification list

* Fix loading indicator on discussion page

* Fix loading indicator on button

* Update more uses of loading indicator

* Fix loading indicator in Search box

* Fix AvatarEditor loading spinner

* Set default spinner props

* Replace "tiny" with "small" in Less

* Improve spinner vertical centring in buttons

* Reduce size specificity

* Use single attribute for block/inline

* Use new display attribute

* Use classes for different sizes

* Use `display=block` by default

js/src/forum/components/AvatarEditor.js

@@ -52,7 +52,13 @@ export default class AvatarEditor extends Component {
           ondragend={this.disableDragover.bind(this)}
           ondrop={this.dropUpload.bind(this)}
         >
-          {this.loading ? <LoadingIndicator /> : user.avatarUrl() ? icon('fas fa-pencil-alt') : icon('fas fa-plus-circle')}
+          {this.loading ? (
+            <LoadingIndicator display="unset" size="large" />
+          ) : user.avatarUrl() ? (
+            icon('fas fa-pencil-alt')
+          ) : (
+            icon('fas fa-plus-circle')
+          )}
         </a>
         <ul className="Dropdown-menu Menu">{listItems(this.controlItems().toArray())}</ul>
       </div>