appearance: add get font list method

- replace 'FontNameList/FontMonoList' with 'GetFontList'
- delete font list cache

Change-Id: Ib2804a991557adaed902a931ee3a75747f5b11ac
tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/fb1090a5f0f44a17b9c2ccc1c9d70dd2/