Update Exposure View, Table and Map

[p-a-s-c-a-l]

As suggested by @mattia-leone in clarity-h2020/csis#154 (comment), the columns HW_POPULATION_DENSITY_CLASS and HW_EXPOSEDQUANTITY have to be made available in EMIKAT View Exposure data (Population) calculated from EMIKAT so that we can show them in the Exposure Table and Map, which ATM just provides POPULATION_TOTAL as HW exposure parameter.

Once this is done, @therter can update the respective resource specification on CSIS-DEV to make the new layers available on the map and update the Exposure Table so that it shows the new columns.

[p-a-s-c-a-l]

I moved the service paths (references) Population Density Class and Number of exposed persons from Resource Heat mortality risk/impact screening to resource European Population Distribution. Now you can see both layers in the Exposure Map:

It would also be good if @humerh or anybody else could update the descriptions of the Heat mortality risk/impact screening and European Population Distribution resources. The changes become available after the next synchronisation from DEV to PROD. See also clarity-h2020/csis#184

Now the question is, whether we want to update the Exposure Table to include HW_POPULATION_DENSITY_CLASS and HW_EXPOSEDQUANTITY or not. If yes, the changes to the EMIKAT View and Table have to be implemented by @humerh and @therter as described above. If not, we can leave it as it is.

BTW, I noticed a big difference between POPULATION_TOTAL and HW_EXPOSEDQUANTITY. It this o.k.?