initial minimal PX4_ROS2 platform and px4_ros2_default build (#20689)

- new ROS2 platform in PX4 intended for creating configs that build and run entirely in ROS2
 - PX4_CONFIG defaults to px4_ros2_default if no config specified and in a colcon workspace with ROS_VERSION=2
 - currently doesn't do much other than allow you to build px4 msgs interface package

src/lib/parameters/CMakeLists.txt

@@ -172,8 +172,8 @@ if(${PX4_PLATFORM} STREQUAL "nuttx")
 endif()
 
 # TODO: find a better way to do this
-if (NOT "${PX4_BOARD}" MATCHES "px4_io")
-	add_library(parameters
+if(NOT "${PX4_BOARD}" MATCHES "px4_io")
+	add_library(parameters STATIC EXCLUDE_FROM_ALL
 		${SRCS}
 		px4_parameters.hpp
 	)
@@ -188,7 +188,7 @@ if (NOT "${PX4_BOARD}" MATCHES "px4_io")
 			-Wno-sign-compare	# TODO: fix and enable
 	)
 else()
-	add_library(parameters ${PX4_SOURCE_DIR}/platforms/common/empty.c)
+	add_library(parameters STATIC EXCLUDE_FROM_ALL ${PX4_SOURCE_DIR}/platforms/common/empty.c)
 endif()
 add_dependencies(parameters prebuild_targets)