CPack: Make usage of STGZ package easier by requiring specifically denying the license terms to abort installation

To make using the generated STGZ easier, require a specific answer to accepting the license terms. Since more moves down one line when '\n' is entered a user may hold enter to paginate through the document. This change prevents the user from accidentally refusing the license terms by holding enter for too long and having to start over.

Topic-rename: cpack-stgz-license-prompt