Allow a channel to have a user scope

Background

See https://eactive.atlassian.net/browse/INTEGRATED-1037#icft=INTEGRATED-1037

Requirements

• Add a new select box field when creating or editing a channel (at /admin/channel/my_channel/edit and /admin/channel/new).

• The new field must be placed below field 'Domains'.

• The new field has a label: 'User scope'

• The select box contains: all user scopes that have been created (https://eactive.atlassian.net/browse/INTEGRATED-1037#icft=INTEGRATED-1037) + the option "No user login allowed". "No user login allowed" is the default value (scope Integrated is not available).

• Store the user scope with the channel.

• Implement the test scenarios (kind of) in Behat

Test scenarios

• Go to /admin/channel/new and /admin/channel/my_channel/edit and check if the select box:

  • has label 'User scope'.

  • is added to the page under field 'Domains'.

  • contains the following options:

    • all user scopes that have been created (https://eactive.atlassian.net/browse/INTEGRATED-1037#icft=INTEGRATED-1037) ,

    • the option "No user login allowed".

  • has a default option: "No user login allowed".

• Check if the chosen 'User scope' is stored within the new or edited channel.