Pass all theme apks to themeservice for processing

3rd party apps expect ACTION_THEME_RESOURCES_CACHED once a theme is installed
regardless of the contents of the theme.

Previously only packages with overlays were passed to the themeservice
for resource processing. The result was packages without overlays would
install and ACTION_THEME_RESOURCES_CACHED would never be broadcasted.

Change-Id: I7cf3f8267805ef2a0626b2690b708e7bbae46bcc
(cherry picked from commit a97c4f34)