simulation organization and cleanup

- new modules/simulation directory to collect all simulators and related modules
 - new Tools/simulation directory to collect and organize scattered simulation submodules, scripts, etc
 - simulation module renamed to simulator_mavlink
 - sih renamed to simulator_sih (not a great name, but I wanted to be clear it was a simulator)
 - ignition_simulator renamed to simulator_ignition_bridge
 - large sitl_target.cmake split by simulation option and in some cases pushed to appropriate modules
 - sitl targets broken down to what's actually available (eg jmavsim only has 1 model and 1 world)
 - new Gazebo consistently referred to as Ignition for now (probably the least confusing thing until we fully drop Gazebo classic support someday)

src/drivers/rpm/CMakeLists.txt

@@ -1 +0,0 @@
-add_subdirectory(pcf8583)

src/drivers/rpm/Kconfig

@@ -1,7 +1,10 @@
-menuconfig DRIVERS_RPM
-	bool "rpm"
-	default n
-	---help---
-		Enable support for rpm
-
-rsource "*/Kconfig"
+menu "RPM"
+    menuconfig COMMON_RPM
+        bool "Common RPM drivers"
+        default n
+        select DRIVERS_RPM_PCF8583
+        select DRIVERS_RPM_RPM_SIMULATOR
+        ---help---
+            Enable default set of RPM drivers
+    rsource "*/Kconfig"
+endmenu

src/drivers/rpm/pcf8583/Kconfig

@@ -0,0 +1,5 @@
+menuconfig DRIVERS_RPM_PCF8583
+	bool "pcf8583"
+	default n
+	---help---
+		Enable support for pcf8583

src/drivers/rpm/rpm_simulator/CMakeLists.txt

@@ -1,6 +1,6 @@
 ############################################################################
 #
-#   Copyright (c) 2020 PX4 Development Team. All rights reserved.
+#   Copyright (c) 2020-2022 PX4 Development Team. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
@@ -31,7 +31,7 @@
 #
 ############################################################################
 px4_add_module(
-	MODULE examples__rpm_simulator
+	MODULE drivers__rpm__rpm_simulator
 	MAIN rpm_simulator
 	SRCS
 		rpm_simulator.cpp

src/drivers/rpm/rpm_simulator/Kconfig

@@ -2,4 +2,4 @@ menuconfig DRIVERS_RPM_RPM_SIMULATOR
 	bool "rpm_simulator"
 	default n
 	---help---
-		Enable support for rpm_simulator
+		Enable support for rpm_simulator

src/drivers/rpm/rpm_simulator/rpm_simulator.cpp

@@ -51,7 +51,6 @@
 extern "C" __EXPORT int rpm_simulator_main(int argc, char *argv[]);
 int rpm_simulator_main(int argc, char *argv[])
 {
-
 	// check input
 	if (argc != 2) {
 		PX4_INFO("Usage: rpm_simulator <published RPM>");