feat: a missing license can say what the device withholds without it (4.15.0)

LicenseDict gets withholds: NotRequired[List[str]]: what a device keeps back
for want of a license while the rest of it answers. A Supermicro X10 with
only SFT-OOB-LIC answers Redfish but withholds its drives and firmware
inventory until DCMS is activated. That makes it partly licensed, not
unlicensed, and the caller can tell the two apart (NetOrk/netork#1111).

tests/test_fact_getters.py

@@ -23,7 +23,15 @@ def test_a_license_says_what_it_is_and_whether_it_holds():
     hints = get_type_hints(LicenseDict)
     assert {"name", "status"} <= set(hints)
     assert LicenseDict.__required_keys__ == frozenset({"name", "status"})
-    assert set(hints) == {"name", "status", "edition", "expires", "detail"}
+    assert set(hints) == {"name", "status", "edition", "expires", "detail", "withholds"}
+
+
+def test_a_missing_license_may_say_what_the_device_withholds_without_it():
+    # A Supermicro X10 with only SFT-OOB-LIC answers Redfish but keeps its drives and
+    # firmware inventory until DCMS is activated: partly licensed, not unlicensed.
+    hints = get_type_hints(LicenseDict)
+    assert hints["withholds"] == list[str] or str(hints["withholds"]).endswith("List[str]")
+    assert "withholds" not in LicenseDict.__required_keys__
 
 
 def test_a_hypervisor_host_says_how_it_stands():