Add entity image (cone-search plot background)

...ce/dataset/components/dataset/dataset-form.component.html

...ance/dataset/components/dataset/dataset-form.component.ts

...ance/dataset/components/dataset/image-form.component.html

...stance/dataset/components/dataset/image-form.component.ts

...rc/app/admin/instance/dataset/components/dataset/index.ts

...n/instance/dataset/containers/edit-dataset.component.html

...min/instance/dataset/containers/edit-dataset.component.ts

client/src/app/metamodel/actions/image.actions.ts

client/src/app/metamodel/effects/image.effects.ts

client/src/app/metamodel/effects/index.ts

client/src/app/metamodel/metamodel.reducer.ts

client/src/app/metamodel/models/image.model.ts

client/src/app/metamodel/models/index.ts

client/src/app/metamodel/reducers/image.reducer.ts

client/src/app/metamodel/selectors/image.selector.ts

client/src/app/metamodel/services/image.service.ts

client/src/app/metamodel/services/index.ts

server/app/dependencies.php

server/app/routes.php

server/src/Action/ImageAction.php