Give Processors a run() function.

So main() can call it, start a Processor linked in to the baseband binary.

firmware/baseband/proc_wideband_spectrum.cpp

@@ -25,6 +25,8 @@
 
 #include "dsp_fft.hpp"
 
+#include "event_m4.hpp"
+
 #include <cstdint>
 #include <cstddef>
 
@@ -72,3 +74,8 @@ void WidebandSpectrum::on_message(const Message* const message) {
 		break;
 	}
 }
+
+void run() {
+	EventDispatcher event_dispatcher { std::make_unique<WidebandSpectrum>() };
+	event_dispatcher.run();
+}