Add option to tag attendees

[mariobehling]

Events have attendees with different roles, e.g. Speakers, Exhibitors etc. Tagging these attendees will help to identify them and also provide an option to add this to the badge.

Please add this feature to the attendee page for organizers.
https://eventyay.com/events/[ID]/tickets/attendees/completed

• Add a column "Tags"
• Add a box to add tags
• Add a check box option to select a) multiple and b) all attendees (similar to Gmail, Github, Wordpress)
• Implement an option to add or delete a tags of ticket holders/attendees (similar to Github)
  • It should be possible to filter all attendees with a certain ticket (filtering is already implemented)
  • It should be possible add a tag to the filtered attendees
  • Each ticket can only have one tag (which is different to Github labels)
• tags could be "Speakers", "Attendees", "VIPs" - organizers should be able to add these tags themselves
• Organizers should be able to edit tags on a pop up page. Similar to the "Edit labels" area of the labels dropdown the tags should be editable.