Fix `just create-vm board/variant`
The empty version was extended to nothing, so the parser in tools/vm/make got confused because one expected argument went missing.
Also make tools/vm/make executable, so the script can actually get started.
The empty version was extended to nothing, so the parser in tools/vm/make got confused because one expected argument went missing.
Also make tools/vm/make executable, so the script can actually get started.