Make sure wasmoo works on windows and update the CI

[hhugo]

See #1796 and https://github.com/ocsigen/js_of_ocaml/actions/runs/12747474600/job/35525613956?pr=1796

### Tasks
- [x] Sys.os_type is not set properly
- [ ] The asset directory is not copied into the inline test sandbox
- [x] There are sometimes errors when filling the asset directory

[vouillon]

There may be a path length issue. One can write to .\inline_test_runner_test_unsafe_set_get_75.bc.wasm.assets6ddc1d.tmp\dune__exe__Inline_test_runner_test_unsafe_set_get_75-a60a749e.wasm, but longer paths such as .\inline_test_runner_jsoo_testsuite_effect.bc.wasm.assets9fa67c.tmp\dune__exe__Inline_test_runner_jsoo_testsuite_effect-07e215e9.wasm.map seem to result in a no such file or directory error.

[hhugo]

The opam package binaryen-bin doesn't seem to work properly on windows. Calling any of the wasm*.exe returns immediately without any output.

[hhugo]

The opam package binaryen-bin doesn't seem to work properly on windows. Calling any of the wasm*.exe returns immediately without any output.

@vouillon, are you able to confirm/refute that ? Maybe it's just me ?

[vouillon]

They seem to work for me. For instance, wasm-merge --version correctly outputs the version. And I have been able to compile wasm_of_ocaml.

[hhugo]

closed by #1799 and ocaml/dune#11307 once merged