Include Waydroid into focal

On top of 16.04 plans (#6 (closed), worked on in parallel) for 20.04 we'll also want to:

• Update libglibutil & libgbinder packaging
  • libglibutil!2 (merged)
  • libgbinder!2 (merged)
• Bring python-gbinder and waydroid itself into focal repos
  • gbinder-python!1 (merged)
  • !4 (merged)
• Add a first-launch dialog to Waydroid when not initialized with images yet
  • Waydroid launcher item simply hidden by default, should show the system settings Waydroid init screen when clicked in the future
• Migrate Anbox storage details to Waydroid
  • Can't calculate size of files under ~/.local/share/waydroid/data/ due to permissions, would likely need proper D-Bus interface to query it from waydroid-container; I have a proof of concept locally but it's not quite ready yet
• Install waydroid into rootfs by default
  • https://gitlab.com/ubports/development/core/seeds/ubuntu-touch/-/blob/focal/touch-core
  • old xenial Anbox stuff: ubports/development/core/seeds/ubuntu-touch@92f916ff
  • ubports/development/core/seeds/ubuntu-touch!75 (merged)
  • Maybe disable waydroid-container.service by default somehow? not really super critical

Some things to work on later:

• Look into integrating https://github.com/waydroid/waydroid-sensors, talks sensorfwd at least and might allow us to "passthrough" many sensors to Waydroid :)
• Install system-settings-waydroid plugin into the rootfs by default once it's done
  • Mockup by @klhio: https://design.penpot.app/#/view/69cd8e21-398c-8036-8001-9bdf14a9d990?page-id=69cd8e21-398c-8036-8001-9bdf14a9d991&section=interactions&index=12&share-id=76981dd7-ec3b-802f-8001-9c033677e202
• Package https://github.com/spyoungtech/pyclip
  • This should enable clipboard sync between Waydroid & Ubuntu Touch native applications (don't know if this has been tried before)
  • Interacting with the Ubuntu Touch clipboard seems more complicated and needs some integration with content-hub(?)