vscode updates and improvements

- fix gazebo SITL debug
     - now prompts you to select vehicle
 - devcontainer.json container support https://code.visualstudio.com/docs/remote/containers
     - this allows you to jump straight into working within a container (px4-dev-nuttx) on a fresh machine
     - also helps with Codespaces https://github.com/features/codespaces
 - plugin updates
    - cpp extension pack, spell checking, CTest support
 - cleanup intellisense
     - the backup tag parser was a resource hog and didn't work very well
 - fix problemMatcher support so that you can click on a build failure

Tools/sitl_run.sh

@@ -2,6 +2,7 @@
 
 
 set -e
+set -o xtrace
 
 if [ "$#" -lt 7 ]; then
 	echo usage: sitl_run.sh sitl_bin debugger program model world src_path build_path