Move "Delete experiment" button to action bar

[cjqian]

No description provided.

[vivtsai]

Are we sure we want to surface it that high? IMO, delete experiment is used much less often so it makes sense for it to be under experiment config settings.

Alternatively, maybe we could change this issue to refactoring the UI to more of a "toolbar" style action bar where actions like delete, save, etc. are icons and thus more lightweight and less distracting?