implements "The Trident of Fish Command"

* The trident of fish command is a terrible artifact.
* The trident is fishbane, and grants you fish-specific
  detection while you wield it.
* Technically, it grants the extrinsic effect Detect_fish via
  a new artifact intrinsic called SPFX_FISH
* The trident exists to suck, and increment your artifact counter
  to make it just that much harder to get one that doesn't suck.