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: @jojobugfree
Reviewed-by: 
Signed-off-by:

From: @JunYuLiu
Reviewed-by: @gemini524
Signed-off-by:

From: @wilfchen
Reviewed-by: @limingqi107,@cristoval
Signed-off-by: @cristoval

Merge pull request !7339 from qujianwei/master

Merge pull request !3921 from vlne-v1/I1Q3KN-interface-changes-cause-network-training-failurs

Merge pull request !3191 from Simson/doc-fix

Merge pull request !3198 from yanghaoran/code_sync_0718

Merge pull request !3036 from jinyaohui/master

Merge pull request !3095 from Simson/push-to-opensource