[SPARK-3623][GraphX] GraphX should support the checkpoint operation

Author: GuoQiang Li <witgo@qq.com>

Closes #2631 from witgo/SPARK-3623 and squashes the following commits:

a70c500 [GuoQiang Li] Remove java related
4d1e249 [GuoQiang Li] Add comments
e682724 [GuoQiang Li] Graph should support the checkpoint operation

(cherry picked from commit e895e0cbecbbec1b412ff21321e57826d2d0a982)
Signed-off-by: Ankur Dave <ankurdave@gmail.com>