Create a LinkedIn video campaign (ad set)

Builds a video sponsored-content campaign: campaign group (a campaign in Campaign Manager), campaign (ad set), video upload (or an existing video URN), dark post and creative (ad). The campaign starts paused and holds everything back (LinkedIn creates groups and creatives only active or draft). Use when: the user has a video and an objective that permits it (VIDEO_VIEW, BRAND_AWARENESS, ENGAGEMENT, WEBSITE_VISIT or WEBSITE_CONVERSION; LEAD_GENERATION needs a Lead Gen Form this server cannot attach, so it is refused). Prefer video_urn when the video is already in the account: uploads are the slowest and most fragile step of this chain. Do not use it for a large file. This server uploads a video in one part; anything LinkedIn wants chunked is refused with instructions to upload once in Campaign Manager and pass the URN instead. That refusal happens after the campaign exists, so pass video_urn when in doubt. Do not call it twice after a failure — it reports what exists and linkedin_add_creative finishes the job. Returns every id created. Judge a video campaign with linkedin_get_engagement_metrics, not CTR: a video ad's job is watch time. Nothing delivers until the campaign is resumed. Say that the campaign is paused when you report the result, with the two links the result gives (LinkedIn Campaign Manager and the campaign's page in Adako), and offer "enable all": one linkedin_resume_campaign call, listed in the result as go_live.enable_all, one approval.