feat: add limit-commits option

[ruyadorno]

Last time I had to fight GitHub API secondary rate limits for a very long-lived LTS release I ended up writing this (based on knowledge shared from @BethGriggs) to help me unblock retrieving a list of commits from branch-diff.

Although it might be functional, the current API here is very clunky and requires the user to find out how many commits are already ignored in order to provide that value to skip-commits and from a combination of skip-commits and limit-commits hopefully cut out a limited enough series of commit that will not trigger GitHub API limits.

Opening this as a draft so that we can discuss better alternatives.