fix: replace "submersion" by "submergence" where appropriate

spec/pab/cloison_aval.spec.ts

spec/pab/cloisons.spec.ts

spec/pab/pab.spec.ts

spec/solveur/solveur.spec.ts

spec/structure/structure_weir_submerged.spec.ts

spec/structure/structure_weir_submerged_larinier.spec.ts

spec/structure/structure_weir_villemonte.spec.ts

src/structure/structure.ts

src/structure/structure_orifice_free.ts

src/structure/structure_rectangular_orifice_free.ts

src/structure/structure_weir_free.ts

src/structure/structure_weir_submerged.ts

src/structure/structure_weir_submerged_larinier.ts

src/structure/structure_weir_villemonte.ts

src/util/message.ts