Themes: Add ability to apply color filters to composed icons

Themes can include one or more of the following filter tags in
assets/icons/res/xml/appfilter.xml

    <!-- HUE filter
         Integer value between -180 and 180 representing the degree.
         0 = no change
    -->
    <filter name="hue">0</filter>

    <!-- SATURATION filter.
         0 = grayscale, 100 = no change, 200 = over saturated
    -->
    <filter name="saturation">0</filter>

    <!-- BRIGHTNESS filter.
         0 = pitch black, 100 = no change, 200 = 200% brightness
    -->
    <filter name="brightness">100</filter>

    <!-- CONTRAST filter.
         -100 = minimal contrast, 0 = no change, 100 = maximum contrast
    -->
    <filter name="contrast">100</filter>

    <!-- ALPHA filter.
         0 = transparent, 100 = opaque
    -->
    <filter name="alpha">75</filter>

    <!-- INVERT filter.
         Valid values are true or false
         true = invert colors
    -->
    <filter name="invert">false</filter>

    <!-- TINT filter.
         A hexadecimal value representing ARGB
    -->
    <filter name="tint">#ff0000ff</filter>

Change-Id: I2431237dd2766176be16c730020557ce87d623e4