IMF/WEO: fix "Subject" dimensions values labels
Reported by @thomasbrand
Problem: for the "WEO Subject" dimension, 2 different dimensions codes have the same label: https://db.nomics.world/IMF/WEO?dimensions=%7B%22weo-subject%22%3A%5B%22NGDP_RPCH%22%2C%22NGDP_R%22%5D%7D
Expected: different labels for different codes
Solution: concatenate the column "Units" of the XLS files to the dimension value label.
Edited by Christophe Benz