On the backend side, adds 3 new parameters to TextPage::findText(),
one bool to enable the feature, one out PDFRectangle to store
the part of the match that falls on the next line, and one out
bool to inform whether hyphen was present and ignored at end of
the previous match part.

For the glib binding, this extends the public PopplerRectangle
struct by new members to hold additional information about
whether the rectangle belongs to a group of rectangles for the
same match, and whether a hyphen was ignored at the end of the
line. Since PopplerRectangle is public ABI, this is done by making
the public PopplerRectangle API return the enlarged struct, and
internally casting to the new struct when required, the new
members are accessible only via accessor functions.

For Qt5 Qt6 bindings, this commit only implements the new flag
Poppler::Page::AcrossLines (but no new function and no new
return data type) and if this flag is passed, the returned
list of ...