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: @yanglf1121
Reviewed-by: @kingxian,@zhunaipan
Signed-off-by: @kingxian

From: @yuchaojie
Reviewed-by: @liangchenghui,@linqingke
Signed-off-by: @liangchenghui

From: @zhangz0911gm
Reviewed-by: @liangchenghui,@zhunaipan
Signed-off-by: @liangchenghui

From: @xiaoyisd
Reviewed-by: @sanjaychan,@jjfeing
Signed-off-by: @sanjaychan

From: @david-he91
Reviewed-by: @liangchenghui
Signed-off-by: @liangchenghui

From: @xiaoyisd
Reviewed-by: @sanjaychan,@chenfei52
Signed-off-by: @sanjaychan

From: @zhangz0911gm
Reviewed-by: 
Signed-off-by:

updating notes of pynative in nn_layer

Merge pull request !8187 from yuchaojie/quant

Merge pull request !8091 from yuchaojie/quant3

Merge pull request !7666 from yuchaojie/quant

Merge pull request !7372 from yuchaojie/quant2