Allow Prettier default for trailing commas, run Prettier on repo

per convo with @claviska

docs/_data/componentList.js

@@ -36,7 +36,7 @@ const components = manifest.modules.flatMap(module => {
         slug: declaration.tagName.replace(/^wa-/, ''),
         methods,
         attributes,
-        properties
+        properties,
       };
     });
 });

docs/_data/componentsBy.js

@@ -6,7 +6,7 @@ const by = {
   event: {},
   method: {},
   cssPart: {},
-  cssProperty: {}
+  cssProperty: {},
 };
 
 function getAll(component, type) {