[UI] Warp Pipe *Input* Icon Color is the same as Filter *Output* Icon Color

For the Warp Pipe Input, the colour of the icons is orange. This is the same as the colour for gas/liquid/conveyer filter Outputs, which is quite confusing at a glance

I propose just keeping the white/mint green from the existing in/out icons, since orange has only ever been used when there are multiple outputs of a single type...!