ui: add delete button

[utnapischtim]

this change enables the delete button on the jobs list.

ERROR:
this change is not working because of an error here:
https://github.com/inveniosoftware/invenio-administration/blob/main/invenio_administration/assets/semantic-ui/js/invenio_administration/src/actions/Actions.js#L34

there error is:

Error: React.Children.only expected to receive a single React element child.

and the warning:

Warning: Failed prop type: Given props {  }: Invalid prop `children` of type `array` supplied to `Dropdown`, expected a single ReactElement.

if i set manually _displayAsDropdown to false it would look like: