Enable sorting by column for Event Series/Event Instances Views

[froboy]

As a content editor I want to sort event series and instances So that they're in the order that is convenient for me.

I'd propose we enable these sorts on these pages:

• /admin/content/events/instances
  • Title
  • Event Date
  • Created
  • Changed
• /admin/content/events/series
  • Title
  • Created
  • Changed

Sorting by "Series Starts" would be nice, but it seems that's already been tried and is ~not possible~ much more complex.

[sarah-halby]

Corresponds to Jira ticket: https://openy.atlassian.net/browse/PRODDEV-182 - we will review during backlog grooming for future enhancements.

[sarah-halby]

Completed in 1.3 release.