Resolve "Streamline the developer's experience with `script/...`"

What does this MR do?

This adds a bunch of useful scripts (that will be improved in the future.

The advantages are:

• script/ is language/technology independent (no need to now that you have to run bundle exec rake -T to see the available commands)
• we can use this convention (https://github.com/github/scripts-to-rule-them-all) for other GitLab-related projects
• the GDK Makefile can be simplified by calling script/bootstrap, script/setup, script/seed etc.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #28781 (moved)