MM-33544 is_following prop in getPosts API methods (#17093)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/store.go

@@ -274,7 +274,7 @@ type PostStore interface {
 	SaveMultiple(posts []*model.Post) ([]*model.Post, int, error)
 	Save(post *model.Post) (*model.Post, error)
 	Update(newPost *model.Post, oldPost *model.Post) (*model.Post, error)
-	Get(ctx context.Context, id string, skipFetchThreads, collapsedThreads, collapsedThreadsExtended bool) (*model.PostList, error)
+	Get(ctx context.Context, id string, skipFetchThreads, collapsedThreads, collapsedThreadsExtended bool, userID string) (*model.PostList, error)
 	GetSingle(id string) (*model.Post, error)
 	Delete(postID string, time int64, deleteByID string) error
 	PermanentDeleteByUser(userId string) error