Add header for custom named containers

[CoreyD97]

Add container header for custom-named containers

[CoreyD97]

This simple change allows PwnFox to be used to send all container names as a header, rather than just colored containers.

This way, you can set up containers like "Low Privilege", "Attacker", "High Privilege", without having to remember which color is for each role etc.

Combined with Logger++ request tags, this makes testing apps with multiple roles a much smoother experience.