feat(structure): Admin has to validate new member joining a structure

...components/claim-structure/claim-structure.component.html

...n/components/claim-structure/claim-structure.component.ts

src/app/admin/models/demandAttachment.model.ts

src/app/app-routing.module.ts

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

src/app/form/form-view/guards/personalOffer.guard.ts

...le-structure-choice/profile-structure-choice.component.ts

src/app/models/pendingStructure.model.ts

src/app/models/user.model.ts

...rofile/profile-structure/profile-structure.component.html

...rofile/profile-structure/profile-structure.component.scss

.../profile/profile-structure/profile-structure.component.ts

src/app/profile/profile.component.html

src/app/profile/profile.component.ts

src/app/profile/services/profile.service.ts

src/app/services/structure.service.ts

src/app/services/user.service.ts

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

...mponents/structure-details/structure-details.component.ts

src/app/structure/enums/joinErrors.enum.ts