Always reserve space for preference icons.

This aligns text on preferences on the same screen when some of them
don't have icons.

- Use a custom layout for
  preference
  EditPreference
  switch preference
  VolumeSeekPreference
  DialogPreferencei
  Restricted*Preference
  DropdownPreference

- Moved related style defs into a new file styles_preference.xml,
  because current styles file is too large to read.
- Switch <PreferenceScreen ...> to <Preference ...> for a bunch of
  regular preferences.
- Also removed some dead style.

Bug: 33430928
Test: runtest --path packages/apps/Settings/tests/app/src/com/android/settings/dashboard/PreferenceThemeTest.java

Change-Id: Ic9b75d3f133f2a83cd999297b8596253d4b10161

src/com/android/settings/DevelopmentSettings.java

@@ -254,7 +254,7 @@ public class DevelopmentSettings extends RestrictedSettingsFragment
     private SwitchPreference mDebugViewAttributes;
     private SwitchPreference mForceAllowOnExternal;
 
-    private PreferenceScreen mPassword;
+    private Preference mPassword;
     private String mDebugApp;
     private Preference mDebugAppPref;
 
@@ -408,7 +408,7 @@ public class DevelopmentSettings extends RestrictedSettingsFragment
 
         mDebugViewAttributes = findAndInitSwitchPref(DEBUG_VIEW_ATTRIBUTES);
         mForceAllowOnExternal = findAndInitSwitchPref(FORCE_ALLOW_ON_EXTERNAL_KEY);
-        mPassword = (PreferenceScreen) findPreference(LOCAL_BACKUP_PASSWORD);
+        mPassword = findPreference(LOCAL_BACKUP_PASSWORD);
         mAllPrefs.add(mPassword);
 
         if (!mUm.isAdminUser()) {
@@ -496,8 +496,7 @@ public class DevelopmentSettings extends RestrictedSettingsFragment
             removePreferenceForProduction(hdcpChecking);
         }
 
-        PreferenceScreen convertFbePreference =
-                (PreferenceScreen) findPreference(KEY_CONVERT_FBE);
+        Preference convertFbePreference = findPreference(KEY_CONVERT_FBE);
 
         try {
             IBinder service = ServiceManager.getService("mount");