MM-11868/MM-12010/MM-12011/MM-12036 Improve post metadata structure (#9693)

* MM-11868/MM-12010/MM-12011/MM-12036 Include dimensions for opengraph and message attachment images in post metadata

* Remove duplicate check from getFirstLinkAndImages

* Add tests for getImagesInMessageAttachments

* Rename PostMetadata.FileInfos to PostMetadata.Files

* Rename Metadata.ImageDimensions to Metadata.Images

model/post.go

@@ -11,7 +11,6 @@ import (
 	"strings"
 	"unicode/utf8"
 
-	"github.com/dyatlov/go-opengraph/opengraph"
 	"github.com/mattermost/mattermost-server/utils/markdown"
 )
 
@@ -83,18 +82,8 @@ type Post struct {
 	PendingPostId string          `json:"pending_post_id" db:"-"`
 	HasReactions  bool            `json:"has_reactions,omitempty"` // Deprecated, do not use this field any more
 
-	// Transient fields populated before sending posts to the client
-	ReactionCounts  ReactionCounts         `json:"reaction_counts" db:"-"`
-	FileInfos       []*FileInfo            `json:"file_infos" db:"-"`
-	ImageDimensions []*PostImageDimensions `json:"image_dimensions" db:"-"`
-	OpenGraphData   []*opengraph.OpenGraph `json:"opengraph_data" db:"-"`
-	Emojis          []*Emoji               `json:"emojis" db:"-"`
-}
-
-type PostImageDimensions struct {
-	URL    string `json:"url"`
-	Width  int    `json:"width"`
-	Height int    `json:"height"`
+	// Transient data populated before sending a post to the client
+	Metadata *PostMetadata `json:"metadata" db:"-"`
 }
 
 type PostEphemeral struct {