Add IGMP, prepend_buffer/parse_buffer, split UDP header, discovery tests, test all

firmware/lib/dispatch.cpp

@@ -6,14 +6,22 @@
 #include "usb_cdc.h"
 #include "timer_queue.h"
 #include "net.h"
+#include "igmp.h"
 #include "debug_log.h"
 #include "hardware/sync.h"
 
 static timer_queue timers;
 
+static void igmp_reannounce() {
+    auto& ns = net_get_state();
+    igmp::send_all_reports(ns.mac, ns.ip, net_send_raw);
+    dispatch_schedule_ms(60000, igmp_reannounce);
+}
+
 void dispatch_init() {
     tusb_init();
     net_init();
+    dispatch_schedule_ms(60000, igmp_reannounce);
     dlog("dispatch_init complete");
 }