adhoc data and pivot table formatting

Any template-less report has the option to enable automatic formatting
based on its type. A "data" report indicated in reports.yaml, a report
without a template with the option "formatting=True", or a true adhoc
report created through the REPL, are all candidates for this feature.

The original Output dataframe, which can also be included now with pivot
tables, will be sent to the spreadsheet formatted as a proper table,
while any pivots created will be formatted as a summary: no gridlines,
subtotal highlighting, frozen panes, and bolded margins.