[device_settings] Provide a reboot dialog after changing the target channel
Switch to using fuchsia.update.ChannelControl, show the target channel
separate from the current channel, as well as adds a reboot confirmation
screen after selecting a new target channel.
In order for the new target channel to take effect, the device needs to
be rebooted.
Bug: 37221, 37233
Test: Manual testing on device
Test: fx run-host-test device_settings_tests
Change-Id: Ib62208d03bed7c6cb2107998817b088699cbc954
3 files changed
