New Launcher feature: "hotseat" icons.

The hotseats are permanent slots on either side of the
AllApps button. Their functions are:

  LEFT/BOTTOM: Phone
    Launched via the hardcoded class name
    com.android.contacts/.ContactsLaunchActivity.

  RIGHT/TOP: Browser
    Launched by querying to see which application is the
    default for URLs, then starting that activity directly.

In the future, it would be ideal to allow an application
with permission to access LauncherProvider to customize
these (icons, contentDescriptions, and Intents).

Bug: 2559083
Change-Id: I56f6e745f8574aa17e28feaa9d2118fb4a715cd4
45 files changed