Cancellable timers: sorted_list::remove, timer cancel, replace done flag with timer cancellation

firmware/lib/dispatch.cpp

@@ -17,8 +17,12 @@ void dispatch_init() {
     dlog("dispatch_init complete");
 }
 
-void dispatch_schedule_ms(uint32_t ms, std::function<void()> fn) {
-    timers.schedule_ms(ms, std::move(fn));
+timer_handle dispatch_schedule_ms(uint32_t ms, std::function<void()> fn) {
+    return timers.schedule_ms(ms, std::move(fn));
+}
+
+bool dispatch_cancel_timer(timer_handle h) {
+    return timers.cancel(h);
 }
 
 [[noreturn]] void dispatch_run(std::span<const handler_entry> handlers) {