rename 'gazebo' simulation to 'gazebo-classic' (#20936)

- use `gazebo-classic` everywhere consistently referring to the original Gazebo (eg version 9,10,11)
   - additional `gazebo_*` helper targets added for compatibility, but warn about deprecation and tell you the new target naming
 - use `gz` everywhere when referring to Gazebo (aka Ignition Gazebo or new Gazebo)

platforms/posix/CMakeLists.txt

@@ -168,7 +168,7 @@ elseif("${PX4_BOARD}" MATCHES "sitl")
 	# px4 Tools files
 	install(
 		PROGRAMS
-			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo/setup_gazebo.bash
+			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo-classic/setup_gazebo.bash
 			${PROJECT_SOURCE_DIR}/Tools/upload_log.py
 		DESTINATION
 			${PROJECT_NAME}/Tools
@@ -182,10 +182,10 @@ elseif("${PX4_BOARD}" MATCHES "sitl")
 			${PROJECT_NAME}/build/px4_sitl_default
 		)
 
-	# sitl_gazebo built plugins
+	# sitl_gazebo-classic built plugins
 	install(
 		DIRECTORY
-			${PX4_BINARY_DIR}/build_gazebo
+			${PX4_BINARY_DIR}/build_gazebo-classic
 		DESTINATION
 			${PROJECT_NAME}/build/px4_sitl_default
 		FILES_MATCHING
@@ -193,22 +193,22 @@ elseif("${PX4_BOARD}" MATCHES "sitl")
 			PATTERN "*.so"
 		)
 
-	# sitl_gazebo dirs
+	# sitl_gazebo-classic dirs
 	install(
 		DIRECTORY
-			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo/sitl_gazebo/models
-			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo/sitl_gazebo/worlds
+			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo-classic/sitl_gazebo-classic/models
+			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo-classic/sitl_gazebo-classic/worlds
 		DESTINATION
-			${PROJECT_NAME}/Tools/simulation/gazebo/sitl_gazebo
+			${PROJECT_NAME}/Tools/simulation/gazebo-classic/sitl_gazebo-classic
 		)
 
-	# sitl_gazebo files
+	# sitl_gazebo-classic files
 	install(
 		FILES
-			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo/sitl_gazebo/CMakeLists.txt
-			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo/sitl_gazebo/package.xml
+			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo-classic/sitl_gazebo-classic/CMakeLists.txt
+			${PROJECT_SOURCE_DIR}/Tools/simulation/gazebo-classic/sitl_gazebo-classic/package.xml
 		DESTINATION
-			${PROJECT_NAME}/Tools/simulation/gazebo/sitl_gazebo
+			${PROJECT_NAME}/Tools/simulation/gazebo-classic/sitl_gazebo-classic
 		)
 
 endif()

platforms/posix/Debug/launch_sitl.json.in

@@ -99,12 +99,12 @@
             "environment": [
                 {
                     "name": "PX4_SIM_MODEL",
-                    "value": "gazebo_iris"
+                    "value": "gazebo-classic_iris"
                 }
             ],
             "externalConsole": false,
-            "preLaunchTask": "gazebo",
-            "postDebugTask": "gazebo kill",
+            "preLaunchTask": "gazebo-classic",
+            "postDebugTask": "gazebo-classic kill",
             "linux": {
                 "MIMode": "gdb",
                 "externalConsole": false,