Enforce ManagedAPIKey for resource ID flag

RequiresManagedResourceID only has meaning for a ManagedAPIKey provider:
ManagedConnectorReady consults it exclusively on that path. A non-managed
provider that set it would advertise normally with the requirement
silently doing nothing. Reject the combination at registration, matching
the ManagedAPIKey/SupportsAPIKey mutual-exclusion guard already in
Register, and cover it with a TestRegistry_Register subtest.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/connector/provider/registry_test.go

@@ -138,6 +138,19 @@ func TestRegistry_Register(t *testing.T) {
 		assert.Contains(t, err.Error(), "mutually exclusive")
 	})
 
+	t.Run("RequiresManagedResourceID requires ManagedAPIKey", func(t *testing.T) {
+		t.Parallel()
+
+		r := provider.NewRegistry()
+		err := r.Register(&provider.Registration{
+			Provider:                  coredata.ConnectorProviderSlack,
+			DisplayName:               "Slack",
+			RequiresManagedResourceID: true,
+		})
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "RequiresManagedResourceID requires ManagedAPIKey")
+	})
+
 	t.Run("duplicate registration", func(t *testing.T) {
 		t.Parallel()