[MM-24177] Adds props to post for front end to know if highlight or not (#14348)

* Add props to post

* Address PR comments

* address PR comments

* Fix styling problems

* Address PR comments

* address PR comments

* Add PR suggestion

* fix usage

* fix error

* remove err

* fix golang lint

model/post.go

@@ -63,8 +63,11 @@ const (
 	POST_PROPS_OVERRIDE_ICON_EMOJI = "override_icon_emoji"
 
 	POST_PROPS_MENTION_HIGHLIGHT_DISABLED = "mentionHighlightDisabled"
+	POST_PROPS_GROUP_HIGHLIGHT_DISABLED   = "disable_group_highlight"
 )
 
+var AT_MENTION_PATTEN = regexp.MustCompile(`\B@`)
+
 type Post struct {
 	Id         string `json:"id"`
 	CreateAt   int64  `json:"create_at"`