Add HTTP TooManyRequests error

Signed-off-by: Brian H <brian.hardock@fermyon.com>

Author: fibonacci1729

sdk/rust/macro/wit/spin-http.wit

@@ -58,4 +58,5 @@ enum http-error {
     invalid-url,
     request-error,
     runtime-error,
+    too-many-requests,
 }

wit/ephemeral/http-types.wit

@@ -55,4 +55,5 @@ enum http-error {
     invalid-url,
     request-error,
     runtime-error,
+    too-many-requests,
 }