将超参数以python字典的形式复制到剪贴板

[ymlgithub]

What would you like to be added:
希望能将每个trial的超参数以python字典的形式导出，放到剪贴板
Why is this needed:
目前搜索到最佳超参数后需要手动复制、粘贴、修改格式
Without this feature, how does current nni work：
修改前：

params = {
    a:1
    b:2
    c:'str'
}

修改后：

params = {
    'a':1,
    'b':2,
    'c':'str'
}

Components that may involve changes:
WebUI
Brief description of your proposal if any:

[yangou1988]

After the discussion of NNI UX design, here are two UI layout and few comments:

UI

1. Put the button 'Copy as Python' to the bottom-left of Parameter
   
2. Remove this expandable parameter
   

Experience

1. Click the 'Copy as Python' button
2. Translate the parameter to Python form
3. Copy it to clipboard
4. A message bar will popup and stay in 3 seconds then disappear