Display model version in Excel export

## Description

Add a bit of info in the Excel export showing what version was used (API + Python version info from https://api.harmonydata.ac.uk/info/version , the front end app knows its own version, so all three versions should be included), what model was used (this was selected in FE and sent to the API), and how to cite Harmony (this info is in the README). I think this would be neater if it was an extra tab in the Excel.

## Rationale

Users need to know how to cite and report their methodologies.