Let protocol handlers decide if they are fetchable (#33573)

This adds a 'is_fetchable()' method on the ProtocolHandler trait that is then used in the fetch code.
The 'data:' protocol handler is updated to return true instead of hardcoding the scheme comparison, as well
as the 'urlinfo:' handler since it's just a testing one.

Signed-off-by: webbeef <me@webbeef.org>

components/net/protocols/data.rs

@@ -54,4 +54,8 @@ impl ProtocolHandler for DataProtocolHander {
 
         Box::pin(std::future::ready(response))
     }
+
+    fn is_fetchable(&self) -> bool {
+        true
+    }
 }