Provide client configuration options to set values that the Pneumatic Armour colours default to.

Context:

• It will allow packmakers to add a bit of polish to their packs
• I noticed that the visor color setting affects the color of the HUD
• I typically configure Xaero's Minimap to be circular with a transparent Aqua Frame
• I like to match this frame with the Pneumatic Helmet HUD by making it Aqua as well, because it makes Xaero's seem like it's part of the HUD
• I figured this would be really cool if a freshly installed modpack could tweak these values to have it work like this out of the box

I am totally OK with a default colour config for the visor piece only, if you're concerned with keeping the default actual armor color theme for (branding...?) purposes

Nah, it can all be configurable. The default is just a neutral grey colour with no real significance attached to it.