Reset, not delete, shipped dictionary configurations

* Enable config model to report if it is derived from a shipped
  default.
* When deleting a config, reset instead of delete if it is
  derived from a shipped default.
* Use existing FW delete-confirmation dialog.
* Allow customization of FW delete-confirmation dialog,
  to be used for more things.
* Part of LT-15468.

Change-Id: I03d17c99c0b2c0b6fb68fd6a73af1442c32f2982