Rework Ignition UI to be based off of the HH3 user interruption api

[kanej]

Update Ignition's UI to take advantage of the user interruption API. In particular it should support in the Ignition UI:

• deployments that read values from configuration variables
• deployments via a ledger

This requires reworking the Ignition UI's refresh so that it supports user interruptions at the UI level (e.g. text being displayed to request a ledger confirmation).