Move all dialog buttons to the right and fix their order

Fixes https://github.com/vector-im/riot-web/issues/5689

Some dialogs had their own CSS that prevented the buttons from being placed in the right spot. This has been fixed by using a generic standard for the buttons. The only strange dialog that needed more CSS was the devtools dialog due to the header.

Not all dialogs have been checked - I spot-checked about half of them and verified the CSS manually on an established account. It's hard to get at all the dialogs without convoluted testing.

src/components/views/elements/DialogButtons.js

@@ -70,15 +70,15 @@ module.exports = React.createClass({
         }
         return (
             <div className="mx_Dialog_buttons">
+                { cancelButton }
+                { this.props.children }
                 <button className={primaryButtonClassName}
-                    onClick={this.props.onPrimaryButtonClick}
-                    autoFocus={this.props.focus}
-                    disabled={this.props.disabled}
+                        onClick={this.props.onPrimaryButtonClick}
+                        autoFocus={this.props.focus}
+                        disabled={this.props.disabled}
                 >
                     { this.props.primaryButton }
                 </button>
-                { this.props.children }
-                { cancelButton }
             </div>
         );
     },