Avoid counting top channel posts for posts made by plugins and OAuth apps (#20943)

* add from_integration prop to oauth posts to:
- oauth app posts
- plugin posts
- slash command responses
- incoming webhook posts

* tests

* include check for bot posts

* use from_plugin and from_oauth_app props

* fix test

* avoid counting top channel posts for posts made by plugins and oauth apps

app/post.go

@@ -203,6 +203,10 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 		post.AddProp("from_bot", "true")
 	}
 
+	if c.Session().IsOAuth {
+		post.AddProp("from_oauth_app", "true")
+	}
+
 	var ephemeralPost *model.Post
 	if post.Type == "" && !a.HasPermissionToChannel(c, user.Id, channel.Id, model.PermissionUseChannelMentions) {
 		mention := post.DisableMentionHighlights()