cubicweb #5278743 dataimport's COPY FROM support strips whitespace from strings [validation pending]

The imported data is mangled.

prioritynormal
typebug
done in3.21.0
load0.500
load left0.000
closed by#efbbf1e93a04 [dataimport] Properly escape strings sent to COPY FROM (closes #5278743)
patch[dataimport] Properly escape strings sent to COPY FROM (closes #5278743) [applied]