Introduce boolean flags to show/hide items in Security & location.

This adds 6 new boolean flags:
config_show_manage_device_admin
config_show_unlock_set_or_change
config_show_screen_pinning_settings
config_show_manage_trust_agents
config_show_show_password
config_show_trust_agent_click_intent

Which when individually set to false, will hide the item from "Security
& location". It will also hide them from surfacing in search results.

Bug:62379222
Test: make RunSettingsRoboTests
ROBOTEST_FILTER=com.android.settings.security
Change-Id: I58d82cbc7f366a9666cdb0f7cd1b90ebbaf418f4

tests/robotests/src/com/android/settings/security/ScreenPinningPreferenceControllerTest.java

@@ -59,8 +59,14 @@ public class ScreenPinningPreferenceControllerTest {
     }
 
     @Test
-    public void isAlwaysAvailable() {
-        assertThat(mController.getAvailabilityStatus()).isEqualTo(AVAILABLE);
+    public void isAvailable_byDefault_isTrue() {
+        assertThat(mController.isAvailable()).isTrue();
+    }
+
+    @Test
+    @Config(qualifiers = "mcc999")
+    public void isAvailable_whenNotVisible_isFalse() {
+        assertThat(mController.isAvailable()).isFalse();
     }
 
     @Test