Instead of always showing "swap", sometimes it shouldn't be shown
at all (i.e. on the first and last screen) and on the NFC screen,
it says "skip".
There is a translated string called "skip_button_label" available
in the AndroidPreferenceFragment library, but I don't want to rely
on that. Prefer to have our awesome translators be in charge of
that label.
bcb47c9490