Add venue statistics to the register

[nuest]

To stats.json, based on https://github.com/codecheckers/register/blob/master/register.csv, write a script that compiles the following information.

• the number of different journals (unique entries in column type)
• the number of checks per journal with some information about each journal/conference based on each unique entry/identifier:
  • logo (from website, see https://codecheck.org.uk/partners/)
  • link to the website (store in yml or JSON file)
  • link to policies page (find yourself, store in yml or JSON file)
  • full name (store locally in yml or JSON file)
• group the venues into three categories: journals, conferences, community

Create a new page that nicely renders the statistics into a dashboard, including

• a timeline of check publications
• logos and numbers of checks

Related to #30