restrict workflows available in the editor

[rrolf]

There may be more editor workflows in the system than you would like to provide to a regular user (lecturer). Based on the context there should be a way to restrict the workflows available in the "select workflow" section.

One idea could be to provide the available workflows with a GET-parameter.

[JamesUoM]

A simple way would be to configure a threshold for the displayOrder value that is sent in the workflows section of edit.json

see https://github.com/opencast/opencast-editor/issues/997