From: @zh_qh
Reviewed-by: 
Signed-off-by:

Move auto monad eliminator out from CSE.
Eliminate auto monad nodes for output node.

From: @chenfei52
Reviewed-by: @hwhewei,@ginfung
Signed-off-by: @ginfung

From: @zh_qh
Reviewed-by: 
Signed-off-by:

From: @zh_qh
Reviewed-by: @hwhewei
Signed-off-by:

From: @lianliguang
Reviewed-by: 
Signed-off-by:

---
Remove the routine of handling isolated nodes in Renormalize.
Add isolated nodes from Parser&Resolver.
Modify isolated nodes handling in FG&Manager.
Optimize the renormalize routines.
Other optimizations.

Use OrderedSet for order list to optimize performance.

The basic idea is: exploits data dependency to control the execution order
of side-effect operations, and keep the semantics of ANF unchanged.

The ControlDepend primitive is removed and there are two primitives added:

1. UpdateState:
```
  a = Assign(para, value)
```
became:
```
  a = Assign(para, value, u)
  u = UpdateState(u, a)
```

2. Load:
```
  x = Add(para, value)
```
became:
```
  p = Load(para, u)
  x = Add(p, value)
  u = UpdateState(u, p)
```

From: @zh_qh
Reviewed-by: @stsuteng,@chenfei52
Signed-off-by: @stsuteng

From: @chenfei52
Reviewed-by: 
Signed-off-by:

normalize codes of session

Merge pull request !8293 from 张清华/grad_opt2

Merge pull request !5918 from flywind/optimizer_pynative_memory