vars+facts: use bwrap only if supported

pkgs/clan-cli/clan_cli/bwrap/tests/test_bwrap.py

@@ -0,0 +1,16 @@
+import sys
+
+import pytest
+from clan_cli.bwrap import bubblewrap_works
+
+
+@pytest.mark.skipif(sys.platform != "linux", reason="bubblewrap only works on linux")
+def test_bubblewrap_works_on_linux() -> None:
+    assert bubblewrap_works() is True
+
+
+@pytest.mark.skipif(
+    sys.platform == "linux", reason="bubblewrap does not work on non-linux"
+)
+def test_bubblewrap_detection_non_linux() -> None:
+    assert bubblewrap_works() is False