Rename two targets to have SettingsLib prefix

- Rename lib name of ActionButtonsPreference and LayoutPreference.
- Remove Settings* prefix for directory name of LayoutPreference.
The LayoutPreference is in settingslib so it's pretty clear
it's a settings widget.

Test: Rebuild SettingsLib and robotest Settings
Change-Id: Ief827067dec85bb5b3ce07d97723c0323aece294
Fixes: 120706174