PR #2491 moved the modules; the instance3d changes follow the new layout:
- tests_instance3d.rs lives in src/tests/instance3d.rs now (declared in src/tests.rs)
- solo_3d moved from render/src/lib.rs to render/src/pipeline.rs, pub(crate),
and its FxHost::layer caller moved to render/src/fx_host.rs
- cmd/create.rs, effects/channel2.rs, gpu/fx_pixel2.rs and render/cache/dependencies.rs
followed their moves automatically (rename detection)