FEAT #10744 TIME 1 add substituted signatures

lang/en.json

lang/fr.json

src/frontend/app/app.component.ts

src/frontend/app/document/document.component.ts

src/frontend/app/login/login.component.ts

src/frontend/app/service/signatures.service.ts

src/frontend/app/signatures/signatures.component.html

src/frontend/app/signatures/signatures.component.scss

src/frontend/app/signatures/signatures.component.ts