Bugfix: Prevent loader in sidebar on add/remove

When adding or removing a public link or collaborator, the respective list view sidebar panels briefly hid the panel and showed a loader instead.
The UI is supposed to show a visual transition of a new list item into the list on adding, as well as a visual transition out of the list on deletion.
This is fixed now by not triggering the loading state on add and remove actions anymore. A loading state is only meant to appear when the user
navigates to the shares of another file/folder.

https://github.com/owncloud/web/issues/2937
https://github.com/owncloud/web/pull/2952
