Break test_tone and test_ppm out of the test_hrt.cpp file into their own respective files.

src/systemcmds/tests/CMakeLists.txt

@@ -59,6 +59,7 @@ set(srcs
 	test_param.c
 	test_parameters.cpp
 	test_perf.c
+	test_ppm.cpp
 	test_ppm_loopback.c
 	test_rc.c
 	test_search_min.cpp
@@ -66,6 +67,7 @@ set(srcs
 	test_servo.c
 	test_sleep.c
 	test_smooth_z.cpp
+	test_tone.cpp
 	test_uart_baudchange.c
 	test_uart_console.c
 	test_uart_loopback.c