reworked cmake, unfortunately a big one due to interdependence

- /mission is a library now, in preparation of unittests (which bring their own main)
- eive-simple is now only available in bsp=arm/q7s (but is still not compiling)
- watchdog and simple are their own executables, not configurations any more
- moved some q7s specific code into /bsp-q7s to flatten if-hierarchy in main CMakeLists.txt
- compiler and linker options are not globally applied to all targets
- linux is the default fsfw osal now, as current code does not compile on hosted

watchdog/Watchdog.h

@@ -2,7 +2,8 @@
 #define WATCHDOG_WATCHDOG_H_
 
 #include <array>
-
+#include <cstdint>
+#include <string>
 
 class WatchdogTask {
 public: