Provide one click to collect all troubleshooting information

[squirrelsc]

What would you like to be added:
Add a command or web button to collect all troubleshooting information, so that user can upload to NNI github for issue.

Why is this needed:
Currently, if the user meets issue on NNI, she/he needs to collect three kinds of information. Users have to learn how to collect them, and those information are missing in many issue reports.

Without this feature, how does current nni work：
Currently, NNI team provides guidance in issue report, to ask user learn and upload information theirselves.

Components that may involve changes:
No sure

Brief description of your proposal if any:
Add a command like nnictl log export, and add a web button like collect log. It can save troubleshooting related information into a zip file, and user can upload it.

The log includes,

1. environment
2. output from nnictl stdout and nnictl stderr
3. nnimanager.log and dispatcher.log