Statistics module refactor

This will be the main MR for @nalonso changes on the statistics module.

• Improve module's tests (!457 (merged) to be merged)
• Update monitor/diagram.py to include the required sections (#1338 (closed))
  • Extend the PDF output with the new data
  • Generate more CSVs files with the new data
  • Modularize it to be more readable
• Include the --include-summary flag to the autosubmit stats command (two flags now)
• Review dependencies (reportlab might be included)
• Review code (nearly done!)
• Test with a real workflow
• @ltenorio and or @mcastril to have a look at the generated reports and confirm it's working as expected (including three PDF files instead of one with three pages?)

We will probably skip the optional options.

CC @bdepaula