pressure loss: add translation for law select entry

refs #585

src/app/calculators/pressureloss/en.json

 {
     "fs_pressureloss_law": "Pressure loss",
     "select_pressurelosstype": "Pressure loss law",
+    "PRESSURELOSSTYPE_0": "Lechapt-Calmon",
+
     "fs_materiau": "Type of material",
     "select_material": "Choice of material",
     "MATERIAL_0": "Unlined cast iron - Coarse concrete (corrosive water)",

src/app/calculators/pressureloss/fr.json

 {
     "fs_pressureloss_law": "Perte de charge",
     "select_pressurelosstype": "Loi de perte de charge",
+    "PRESSURELOSSTYPE_0": "Lechapt-Calmon",
+
     "fs_materiau": "Type du matériau",
     "select_material": "Choix du matériau",
     "MATERIAL_0": "Fonte ou acier non revêtus - Béton grossier (eau corrosive)",