Convert `width.module.css` to CSS modules (#41359)

frontend/src/metabase/components/FieldSet.tsx

@@ -43,7 +43,7 @@ export function FieldSet({
           {required && <span>&nbsp;*</span>}
         </legend>
       )}
-      <div data-testid="field-set-content" className="w-full">
+      <div data-testid="field-set-content" className={CS.wFull}>
         {children}
       </div>
     </fieldset>

frontend/src/metabase/css/core/width.module.css

-:global(.w-full),
-.w-full,
 .wFull {
   width: 100%;
 }