RCFilters: Allow experimental live update feature to be enabled with query string parameter

For testing. Adding ?liveupdate=1 to the URL will unhide the live update button. Bug: T167743 Change-Id: I2696da959d34adf952f7f2fa6477ab756ef259bd

Author: catrope

resources/src/mediawiki.rcfilters/ui/mw.rcfilters.ui.FilterWrapperWidget.js

@@ -58,7 +58,11 @@
 $bottom = $( '<div>' )
 .addClass( 'mw-rcfilters-ui-filterWrapperWidget-bottom' );
 
-if ( mw.config.get( 'wgStructuredChangeFiltersEnableLiveUpdate' ) ) {
+if (
+mw.config.get( 'wgStructuredChangeFiltersEnableLiveUpdate' ) ||
+// Allow users to enable live update with ?liveupdate=1
+new mw.Uri().query.liveupdate
+) {
 $bottom.append( this.liveUpdateButton.$element );
 }