New threadpool

- removed some whitespace noise.
 - cleaned up CMakeLists.txt
 - reintegrated task_manager.c into thread-pool.c
 - cleaned up some unnecessary code

Co-authored-by: Cedric Roux <cedric.roux@eurecom.fr>
Co-authored-by: Mikel Irazabal <mikel.irazabal@openairinterface.com>

radio/USRP/usrp_lib.cpp

@@ -49,6 +49,7 @@
 #include "common/utils/LOG/log.h"
 #include "common_lib.h"
 #include "assertions.h"
+#include "system.h"
 
 #include "common/utils/LOG/vcd_signal_dumper.h"