Media Previews (#11888)

Co-authored-by: Niels Lyngsø <nsl@umbraco.com>
Co-authored-by: Mads Rasmussen <madsr@hey.com>
Co-authored-by: Paul Johnson <pmj@umbraco.com>

src/Umbraco.Web.UI.Client/gulpfile.js

@@ -31,6 +31,8 @@ const coreBuild = parallel(dependencies, js, less, views);
 // ***********************************************************
 
 exports.build = series(coreBuild, testUnit);
+exports.buildDev = series(setDevelopmentMode, coreBuild);
+
 exports.coreBuild = coreBuild;
 exports.dev = series(setDevelopmentMode, coreBuild, runUnitTestServer, watchTask);
 exports.watch = series(watchTask);