feat(admin): add visualisation of unclaimed structure

src/app/admin/admin-pannel.scss

src/app/admin/admin.module.ts

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

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

src/app/admin/components/panel/panel.component.html

...ents/structures-list/admin-structures-list.component.html

...s/structures-list/admin-structures-list.component.spec.ts

...onents/structures-list/admin-structures-list.component.ts

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

src/app/admin/services/admin.service.ts

src/app/shared/enum/adminPanel.enum.ts