Particle Modifier: "Convert" puts new objs in new collection, add "Convert to Single Mesh" , and "mesh data single-user" option.

1. When a particle system is rendering particles as objects (or a collection of objects), you're able to convert those particles to separate meshes. It would be a good, possibly quick fix to have the "Convert" button in the particle modifier properties put all newly converted objects into a new collection within the collection that the object with the particle system is in.

2. Having a "Convert to Single Mesh" option would be good as well, in case someone wants to make all the particle objects be one mesh. I would personally use this in any scene, whether it's going to be used in real time or in an offline renderer, if the objects are not going to be animated or used in physics, so as to render faster and using less memory. The resulting object will need to have its own mesh data, so as to not overwrite the mesh data of the object that is/was being used in the particle system that was calling it in the first place.

EDIT: I've tried editing the modifier myself but I was unable. However, I believe that a good way to implement this is to simply add a new object to the scene, and then add all the particles object mesh data into that single object. This would be better than what I currently do, which is convert all particles to separate objects, select all those objects, make one of them the active object, make the active object's mesh data a single-user, and then join all the objects. This is slow because the computer takes a while to calculate during the "convert" and "join all objects" steps. So putting these into one step may be faster. Or at least more straight-forward.

3. When converting the particle system to separate objects (that is, the default "Convert" button) an option to set the resulting converted objects to have its own, single-user mesh data would be good. This can be for all the objects sharing their own mesh data, not using the original particle instanced object mesh data, or it can be for each separate obj having their own mesh data.