Make file and/or buffer names available to org-clock-csv-row-fmt functions

[sshaw]

Currently the function is limited to what's returned by org-clock-csv--parse-element but it would be very useful if the filename (or buffer) was made available so that one could extract additional info and place it in the spreadsheet.

I can submit a PR if interested.

[atheriel]

Filenames do indeed sound like a nice parameter to have made available. Feel free to submit a PR.