feat: handle 0 as default of equipments

src/app/form/structure-form/form.component.html

src/app/form/structure-form/form.component.scss

src/app/form/structure-form/form.component.ts

src/app/models/structure.model.ts

...onents/structure-details/structure-details.component.html

src/app/utils/CustomRegExp.ts