Everywhere: Remove a bunch of redundant 'AK::' namespace prefixes

This is basically just for consistency, it's quite strange to see
multiple AK container types next to each other, some with and some
without the namespace prefix - we're 'using AK::Foo;' a lot and should
leverage that. :^)

Userland/Utilities/uniq.cpp

@@ -89,7 +89,7 @@ int main(int argc, char** argv)
             continue;
 
         fputs(current->buf, outfile);
-        AK::swap(current, previous);
+        swap(current, previous);
         first_run = false;
     }