feat: initial booting kernel, copy libc stuff from myke

yak-kernel/src/rt/kmain.c

@@ -0,0 +1,13 @@
+#include <yak/rt/kmain.h>
+#include <yak/rt/panic.h>
+#include "yak/platform/generic/platform.h"
+
+void kmain() {
+    // kmain is called from one of the bootloader implementations
+
+    // perform platform specific initialisation
+    platform_init();
+
+    // this should (eventually) be unreachable
+    panic("End of kmain");
+}