Add (basic) support for `gset` and `gset_disj` cameras to `set_solver`.
This came up in a discussion at Mattermost: https://mattermost.mpi-sws.org/iris/pl/gnxuzycpzjdpxdi1swtcsr8fwa
This came up in a discussion at Mattermost: https://mattermost.mpi-sws.org/iris/pl/gnxuzycpzjdpxdi1swtcsr8fwa