bba5cd63e81a491c28eddc14e4087ba179794a3c gui: installer: convey registering on a signing device isn't always required (Antoine Poinsot)
Pull request description:
As discussed in #545, in some cases we nudge the user to register the descriptor on their signing device although they might not have one. Those cases only ever arise when importing a descriptor (either when recovering from backup or participating in the creation of a descriptor on another laptop), since when the descriptor is created beforehand we can simply detect whether a signing device was used and thereby needs to be registered (implemented since https://github.com/wizardsardine/liana/pull/470).
Therefore, detect when the registration step arises as part of an import process and if so adjust the language to convey registration on a signing device may not be necessary.
Result:

Fixes#545.
ACKs for top commit:
edouardparis:
ACK bba5cd63e81a491c28eddc14e4087ba179794a3c
Tree-SHA512: 5b25b0c980f3e57563fc3c301802a7c4da50d7c80802d3e6a7517f98ee1da60e9d5ebe890ce3b8c34ca882220d920e31c59b79877c9e8f48b72b092d3809acda