LibWeb: Implement navigator.{plugins,mimeTypes}

Author: https://github.com/Lubrsi
Commit: 4d0277cd9a
Pull-request: https://github.com/SerenityOS/serenity/pull/17658
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibWeb/HTML/PluginArray.idl

@@ -0,0 +1,9 @@
+#import <HTML/Plugin.idl>
+
+[Exposed=Window, LegacyUnenumerableNamedProperties, UseNewAKString]
+interface PluginArray {
+    undefined refresh();
+    readonly attribute unsigned long length;
+    getter Plugin? item(unsigned long index);
+    getter Plugin? namedItem(DOMString name);
+};