[Submissions] Add target collection to the submission form

This MR adds the capability for new Submissions to specify an optional target Collection, e.g. when it is a Lecture Notes publication to be published in a Les Houches Collection.

Details

• For a Collection to be specified, at least one of the Submission's authors must be in the list of the Collection's expected authors.
• A new expected_editors field is defined on Collections that will set the Submissions' Fellowships if populated.
• Currently, the Collections field only shows if the target journal is Lecture Notes, but this can be trivially extended.
• Git repo creation takes into account different production templates based on a Series or Collection specifications.
• Collection information is shown in the Production Stream page.