[Icons] Fix aliases and default_attributes config types for config/reference.php

Author: Kocal

src/Icons/src/DependencyInjection/UXIconsExtension.php

@@ -63,7 +63,9 @@ public function getConfigTreeBuilder(): TreeBuilder
                                 ->info('Override default icon attributes for icons in this set.')
                                 ->example(['class' => 'icon icon-acme', 'fill' => 'none'])
                                 ->normalizeKeys(false)
-                                ->variablePrototype()
+                                ->useAttributeAsKey('key')
+                                ->scalarPrototype()
+                                    ->cannotBeEmpty()
                                 ->end()
                             ->end()
                         ->end()
@@ -80,7 +82,8 @@ public function getConfigTreeBuilder(): TreeBuilder
                         'privacy' => 'bi:cookie',
                     ])
                     ->normalizeKeys(false)
-                    ->scalarPrototype()
+                    ->useAttributeAsKey('key')
+                    ->stringPrototype()
                         ->cannotBeEmpty()
                     ->end()
                 ->end()