Added "required" to igvc_control.launch. Tested by killing the igvc_c…

[NicholasLeone]

Add "required" to igvc_control node

Added "required" attribute to igvc_control node. I tested the attribute by killing the igvc_control node and seeing the entire stack die.

Self Checklist

• [X] I have formatted my code using make format
• [X] I have tested that the new behaviour works