Fix #5360: Use OpenGraph's og:image metadata for posts.

* Add og:image:width, og:image:height, and og:image:type tags.
* Use og:video tags for videos.
* Use 720x720 instead of 150x150 preview images for videos.
* Add duration tag to JSON-LD data for videos.
* Add OpenGraph tags to media assets show page.
* Respect Twitter max image size limits.
* Don't include OpenGraph image tags when someone shares a plain https://danbooru.donmai.us link
  with no tag search. This caused random potentially NSFW images to be shown when someone shared a
  https://danbooru.donmai.us link on social media, which could be cached for long periods of time.

app/helpers/seo_helper.rb

@@ -14,19 +14,6 @@ module SeoHelper
     "#{Danbooru.config.canonical_app_name} is the original anime image booru. Search millions of anime pictures categorized by thousands of tags."
   end
 
-  # https://developers.google.com/search/docs/data-types/video#video-object
-  def json_ld_video_data(post)
-    json_ld_tag({
-      "@context": "https://schema.org",
-      "@type": "VideoObject",
-      name: page_title,
-      description: meta_description,
-      uploadDate: post.created_at.iso8601,
-      thumbnailUrl: post.media_asset.variant("360x360").file_url,
-      contentUrl: post.file_url,
-    })
-  end
-
   def json_ld_website_data
     urls = [
       Danbooru.config.twitter_url,