FEAT #11788 TIME 2:50 Substituted signatures are back

lang/en.json

lang/fr.json

rest/index.php

sql/20XX.sql

sql/structure.sql

src/app/document/controllers/DocumentController.php

src/app/user/controllers/SignatureController.php

src/frontend/app/document/document.component.html

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

src/frontend/app/profile/profile.component.html

src/frontend/app/profile/profile.component.ts

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

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

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