Removed space tokens

[lukasoppermann]

Summary

[!CAUTION] This can only be considered a minor change if we remove any use of --space tokens before we merge and release this.

This PR removes the --space tokens. They are deprecated and users should use --base-size tokens instead.

However, they are still in use:

• GitHub
• Primer (only 2 cases)
  • https://github.com/primer/react/pull/4598

Tasks

• [ ] ~update styleLint plugin: https://github.com/primer/stylelint-config/blob/86cf24f5c1f3f51b5085a5808a5406bc04e47b68/tests/fixtures/good/example.module.css#L131 also to suggest base size for 2px and 6px~
• [x] fix uses for GitHub