Tweak tablet keyboard design

This change introduces,
- center align "More" key label
- remove drop shadow from key label
- darker key label color when manual temporary upper case
- narrower pop up mini keyboard
- remove unnecessary key background from pop up mini keyboard
- smaller key label in portrait

Bug: 3216592
Change-Id: I77e0733f467a88aa32e09fcbace56fe08f755229
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index ee4ec05..ef7a968 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -25,8 +25,8 @@
              checkable+checked+pressed. -->
         <attr name="keyBackground" format="reference" />
 
-        <!-- Size of the text for character keys. -->
-        <attr name="keyTextSize" format="dimension" />
+        <!-- Size of the text for one letter character keys. -->
+        <attr name="keyLetterSize" format="dimension" />
 
         <!-- Size of the text for custom keys with some text and no icon. -->
         <attr name="labelTextSize" format="dimension" />
@@ -34,6 +34,9 @@
         <!-- Color to use for the label in a key. -->
         <attr name="keyTextColor" format="color" />
 
+        <!-- Color to use for the label in a key when in disabled state. -->
+        <attr name="keyTextColorDisabled" format="color" />
+
         <!-- Layout resource for key press feedback.-->
         <attr name="keyPreviewLayout" format="reference" />
 
@@ -56,10 +59,12 @@
         <attr name="shadowRadius" format="float" />
         <attr name="backgroundDimAmount" format="float" />
 
-        <attr name="keyTextStyle">
+        <attr name="keyLetterStyle">
+            <!-- This should be aligned with Typeface.NORMAL etc. -->
             <enum name="normal" value="0" />
             <enum name="bold" value="1" />
             <enum name="italic" value="2" />
+            <enum name="boldItalic" value="3" />
         </attr>
 
         <attr name="colorScheme">