Added the possibility to animate X and refactoring

A viewstate can now animate its X value.
This also refactors the animation logic such that
an application when an animation is running will
update the existing animation nicely.

Test: manual, observe views animating in X
Bug: 32437839
Change-Id: Ic091d87e530af793281ca3f2b1e9370ff5dac236
diff --git a/packages/SystemUI/res/values/ids.xml b/packages/SystemUI/res/values/ids.xml
index 94d79f2..8c80c71 100644
--- a/packages/SystemUI/res/values/ids.xml
+++ b/packages/SystemUI/res/values/ids.xml
@@ -16,18 +16,21 @@
   -->
 
 <resources>
+    <item type="id" name="translation_x_animator_tag"/>
     <item type="id" name="translation_y_animator_tag"/>
     <item type="id" name="translation_z_animator_tag"/>
     <item type="id" name="alpha_animator_tag"/>
     <item type="id" name="top_inset_animator_tag"/>
     <item type="id" name="height_animator_tag"/>
     <item type="id" name="shadow_alpha_animator_tag"/>
+    <item type="id" name="translation_x_animator_end_value_tag"/>
     <item type="id" name="translation_y_animator_end_value_tag"/>
     <item type="id" name="translation_z_animator_end_value_tag"/>
     <item type="id" name="alpha_animator_end_value_tag"/>
     <item type="id" name="top_inset_animator_end_value_tag"/>
     <item type="id" name="height_animator_end_value_tag"/>
     <item type="id" name="shadow_alpha_animator_end_value_tag"/>
+    <item type="id" name="translation_x_animator_start_value_tag"/>
     <item type="id" name="translation_y_animator_start_value_tag"/>
     <item type="id" name="translation_z_animator_start_value_tag"/>
     <item type="id" name="alpha_animator_start_value_tag"/>