add evaluate_code render profile

[KaiWaldrant]

Describe your changes

For some of the pages, only render executable code when the 'evaluate_code' profile is active.

Issue ticket number and link

Closes #207

Checklist before requesting a review

• [x] I have performed a self-review of my code

• Check the correct box. Does this PR contain:

  • [ ] Breaking changes
  • [x] New functionality
  • [ ] Major changes
  • [ ] Minor changes
  • [ ] Bug fixes

• [x] Proposed changes are described in the CHANGELOG.md

• [x] CI Preview succeeds and looks good!

[github-actions[bot]]

[KaiWaldrant]

The arg -- profile evaluate_codedoesn't seem to work when you already rendered or previewed the site. You need to remove _site and _freeze directories. Added this instruction to the README

[KaiWaldrant]

LGTM if the checks are ok.