Added global_fragility_vulnerability_2018 of Martins and Silva

As described in https://git.gfz-potsdam.de/dynamicexposure/collaboration/-/issues/471, the fragility and vulnerability files are added to avoid uploading them to the losscalculator repository. Please let me know any issue or inconsistency that you can see.
\approve @ds @cnievas
\rfc @shinde @LaurensJN