Add UI for mainline modules licenses.

Added a module licenses option that lives in Legal information settings.
Clicking that option opens module licenses page, which displays every
module by name, filtered to exclude modules without license files.
Clicking a module in the list opens HTMLViewer.

Created ModuleLicensesProvider, a new ContentProvider that serves as a
redirect for the Uris sent to HTMLViewer so that they open asset files.
In order to provide the redirect, the provider will write the license file
to a file in Settings' cache directory when the license does not exist
in the cache or is outdated. The provider then opens that cached file.

Fixes: 135183006
Test: robotests
Change-Id: I7d69da34780c8c4efb150d0c0411078c12bc80d8

src/com/android/settings/core/gateway/SettingsGateway.java

@@ -72,6 +72,7 @@ import com.android.settings.deviceinfo.StorageDashboardFragment;
 import com.android.settings.deviceinfo.StorageSettings;
 import com.android.settings.deviceinfo.aboutphone.MyDeviceInfoFragment;
 import com.android.settings.deviceinfo.firmwareversion.FirmwareVersionSettings;
+import com.android.settings.deviceinfo.legal.ModuleLicensesDashboard;
 import com.android.settings.display.NightDisplaySettings;
 import com.android.settings.dream.DreamSettings;
 import com.android.settings.enterprise.EnterprisePrivacySettings;
@@ -175,6 +176,7 @@ public class SettingsGateway {
             UserDictionarySettings.class.getName(),
             DisplaySettings.class.getName(),
             MyDeviceInfoFragment.class.getName(),
+            ModuleLicensesDashboard.class.getName(),
             ManageApplications.class.getName(),
             FirmwareVersionSettings.class.getName(),
             ManageAssist.class.getName(),
@@ -318,6 +320,7 @@ public class SettingsGateway {
             Settings.DateTimeSettingsActivity.class.getName(),
             Settings.EnterprisePrivacySettingsActivity.class.getName(),
             Settings.MyDeviceInfoActivity.class.getName(),
+            Settings.ModuleLicensesActivity.class.getName(),
             UserBackupSettingsActivity.class.getName(),
     };
 }