Conversations UX polish pass

- adjust position of expanded group avatar to remain vertically
    centered with title

  - adjust top padding of guts to match that of conversation layout

  - vertically align app name and time in the conversation header

  - clean up some of our XML styles

Fixes: 157757386
Test: manual, visual
Change-Id: I5eb774b44ce641a97c5deb706711f3b252e6554e

core/java/com/android/internal/widget/ConversationLayout.java

@@ -761,9 +761,13 @@ public class ConversationLayout extends FrameLayout
                 // group
                 : mExpandedGroupMessagePadding;
 
+        int iconPadding = mIsOneToOne || mIsCollapsed
+                ? mConversationIconTopPadding
+                : mConversationIconTopPaddingExpandedGroup;
+
         mConversationIconContainer.setPaddingRelative(
                 mConversationIconContainer.getPaddingStart(),
-                mConversationIconTopPadding,
+                iconPadding,
                 mConversationIconContainer.getPaddingEnd(),
                 mConversationIconContainer.getPaddingBottom());