Create a script to generate `monorepo-example`

[aguschin]

We use https://github.com/iterative/monorepo-example in MR docs to explain how Studio MR works with monorepos. For easier support, we need to

• create a script to generate it in this repo
• do that by copying existing repos - no need to re-run all scripts
• copy all commits (not only 1 for each repo)