make profile plan information easier to access

The `flux/query` plan field of the query profiler results is crucial for understanding how a query has been mapped to the underlying operations, and in particular which parts of the query have been pushed down to the storage layer.

Although you can hover over the field in the "raw data" view, it's only possible to get hold of the actual text by downloading the CSV as a file and copy and pasting from within that. Selecting the text in the field and copying it removes the newlines which hold important semantic information.

Ideally the UI would have the capability to show the graph graphically directly in the page, but failing that, it would be nice if it was possible to copy a text field including line breaks.