Fix dispatch for remove_all_from_space!

[simsurace]

This fixes #1104.

• Restrict the method in discrete.jl to discrete spaces
• Add a test that defines a new space as described in the dev docs and checks that adding and removing agents works. The test fails without the next step
• Add a generic fallback that makes the new test pass
• Add a note in the dev docs that this is a candidate to be overloaded for performance

[Tortar]

Cool, thank you, unfortunately tests are broken on 1.11.1, but I suppose they run locally, right? Can you bump the version so that we release it right away?

[simsurace]

They do pass on 1.10 locally. I don't understand the failure on 1.11 unfortunately. I'll bump.

[Tortar]

sorry, thought you had bumped :Q