Move from optparse to optimist or micro-optparse

In order to avoid the scripting of keeping the option section in the README.md up to date, I could convert options-parser.rb to use optimist, which has less clutter and could thus be linked to.

• https://www.manageiq.org/optimist/
• https://florianpilz.github.io/micro-optparse/
• https://gitlab.com/gitlab-org/quality/performance/blob/main/bin/generate-gpt-data