Online Accounts setup for Ubuntu Touch

Merge proposals dependent on lp://qastaging/~mardy/ubuntu-system-settings-online-accounts/single-new-hook-1596843

  1. single-new-hook-1596843
  2. Dependent merge proposals

lp://qastaging/~mardy/ubuntu-system-settings-online-accounts/single-new-hook-1596843 has no merge proposals.