Fix for T61187.
Some properties were accidentally hidden for particle fluids. Here's a fix.
- Made sure we show the Forces and Integration subpanels for particle fluids
- Slightly re-ordered the subpanels here, so that the same subpanels are at the top for Newtonian and Fluid particles
- Separated the Fluid Interaction subpanel so we can give it a unique name
- Removed lingering unnecessary 'Keys' label in the Keyed physics