encode: Implement Flush for legacy compatibility

(By sponsor request)

modules/caddyhttp/encode/encode.go

@@ -307,6 +307,14 @@ func (rw *responseWriter) FlushError() error {
 	return http.NewResponseController(rw.ResponseWriter).Flush()
 }
 
+// Flush calls FlushError() and simply discards any error. It is only implemented for backwards
+// compatibility with legacy code that does not use FlushError; we know at least one sponsor
+// needs this. It should not be relied upon as a stable part of the exported API, as it may be
+// removed in the future.
+func (rw *responseWriter) Flush() {
+	_ = rw.FlushError()
+}
+
 // Write writes to the response. If the response qualifies,
 // it is encoded using the encoder, which is initialized
 // if not done so already.