Improve make_component.sh

[fniephaus]

This PR improves make_component.sh in the following ways:

• "Exit immediately if a command exits with a non-zero status." (set -e)
• Fix incorrect rm -rf COMPONENT_DIR and add user prompt before deleting directory
• Suggest to run mvn package when simplelanguage.jar is not found
• Use pushd/popd in favor of cd
• Mark variables as readonly
• Minor consistency fixes

[boris-spas]

Could you please rebase? I merged a PR that made some changes to the script in question and re-enabled the part of the gate that checks the components.

[fniephaus]

Done! PTAL