Support the rich content for accessibility service (1/n)

Goal: 1. let third party developer can use html text that include from their local image file and
         animated image instead of only plain text to rich their content.
      2. Avoid malicious links made by third party developer

Action: 1. Add html, static text, and animated image preferences.
        2. Add android:AnimatedImageDrawable, and android:htmlDescription attributes.
        3. Fine-tune interface and integration
        4. Add custom tag filter

Bug: 136292241
Test: Maunal & make RunSettingsRoboTests
Change-Id: I82cd5319efb7faa1ff7e8354a279828fce5135b8