Copy drafts

Deprecated: use research.drafts.copy.v2 (research_drafts_copy_v2) for native audio; this version refuses to copy a study that shows audio (409 PRECONDITION_FAILED, details.reason not_copyable). Copy a Research campaign's saved Custom study into a new unfinished draft of the signed-in user's: its material and questions as frozen, its business profile, its schedule (once, weekly or monthly) and its roster's customers as the draft's picked customers (none when the roster holds more than a draft can pick). Send a new draft id as id and the campaign as campaignId; the copy is that draft at revision 1, which research_drafts_get_v2 reads and research_drafts_save_v2 edits. Launching it (research_campaigns_launch) starts a new campaign; the copied one stays as it ran. A study other than Custom is refused 409 PRECONDITION_FAILED (details.reason not_copyable); a deleted, unknown or other tenant's campaign answers 404. Drafts belong to the user who saves them, so an API key cannot copy one.