Update background color of the xml based weather widget

- To closely match the appWidgetBackground color used in glance.

Author: shamalip

samples/user-interface/appwidgets/src/main/res/drawable-v21/app_widget_background.xml

@@ -23,5 +23,5 @@ appWidgetRadius attribute value
     android:shape="rectangle">
 
     <corners android:radius="?attr/appWidgetRadius" />
-    <solid android:color="?android:attr/colorBackground" />
+    <solid android:color="@color/colorAppWidgetBackground" />
 </shape>

samples/user-interface/appwidgets/src/main/res/values-night-v31/glance_colors.xml

@@ -47,6 +47,7 @@
     <color name="colorOnError">@color/m3_sys_color_dark_on_error</color>
     <color name="colorErrorContainer">@color/m3_sys_color_dark_error_container</color>
     <color name="colorOnErrorContainer">@color/m3_sys_color_dark_on_error_container</color>
+    <color name="colorAppWidgetBackground">@android:color/system_accent2_800</color>
 
     <color name="textColorPrimary">@color/m3_dynamic_dark_default_color_primary_text</color>
     <color name="textColorPrimaryInverse">@color/m3_dynamic_default_color_primary_text</color>

samples/user-interface/appwidgets/src/main/res/values-night/glance_colors.xml

@@ -42,6 +42,7 @@
     <color name="colorOnError">@color/m3_sys_color_dark_on_error</color>
     <color name="colorErrorContainer">@color/m3_sys_color_dark_error_container</color>
     <color name="colorOnErrorContainer">@color/m3_sys_color_dark_on_error_container</color>
+    <color name="colorAppWidgetBackground">#ff20333d</color>
 
     <color name="textColorPrimary">@color/m3_dark_default_color_primary_text</color>
     <color name="textColorPrimaryInverse">@color/m3_default_color_primary_text</color>

samples/user-interface/appwidgets/src/main/res/values-v31/glance_colors.xml

@@ -48,6 +48,7 @@
     <color name="colorOnError">@color/m3_sys_color_light_on_error</color>
     <color name="colorErrorContainer">@color/m3_sys_color_light_error_container</color>
     <color name="colorOnErrorContainer">@color/m3_sys_color_light_on_error_container</color>
+    <color name="colorAppWidgetBackground">@android:color/system_accent2_50</color>
 
     <color name="textColorPrimary">@color/m3_dynamic_default_color_primary_text</color>
     <color name="textColorPrimaryInverse">@color/m3_dynamic_dark_default_color_primary_text</color>

samples/user-interface/appwidgets/src/main/res/values/glance_colors.xml

@@ -42,6 +42,7 @@
     <color name="colorOnError">@color/m3_sys_color_light_on_error</color>
     <color name="colorErrorContainer">@color/m3_sys_color_light_error_container</color>
     <color name="colorOnErrorContainer">@color/m3_sys_color_light_on_error_container</color>
+    <color name="colorAppWidgetBackground">#ffe0f3ff</color>
 
     <color name="textColorPrimary">@color/m3_default_color_primary_text</color>
     <color name="textColorPrimaryInverse">@color/m3_dark_default_color_primary_text</color>