UX improvement for showing Error log

[QuanluZhang]

What would you like to be added: When an experiment is failed, users have to go to "~/nni/experiments//log/" to check nnimanager.log and dispatcher.log. For some users, they may not know where these log files are. Even if they know the location of these log files, every time the experiment is failed, they have to check those files manually. If users can click and view the content of these files directly through webui, it would be more friendly and convenient.

Why is this needed: more convenient

Without this feature, how does current nni work：stated above

Components that may involve changes: webui

[yangou1988]

Click/hover Erro 'i' button > Erro information > Click 'Learn more'

Anchored Dispatcher Log / NNI Manager Log from right side
So users can check and preview the log information (Last 4096 bytes) at NNI portal directly and then download or view the full log.

Also redesign the UX of Download in the navigation

Click Download > Click Experiment parameters

Anchored Experiment parameters from right side as same as Dispatcher Log / NNI Manager Log