Refactor external camera system

[JonnyOThan]

The external camera page has too much control over the camera names and properties. Instead, these properties should be specified in partmodules on the cameras themselves. Additionally, it should be built in a way that other mods can easily include their own effects and customizations like in #34 . Also keep in mind potentially getting a camera feed from other vessels, like for BDA, CCTV, or OCISLY.