Honor --max-peers if --min-peers is not specified (#8087)

* Change interpretation min and max peers

* Only min specified -> Set min to that value and max to default
* Only max specified -> Set min and max to that value
* Both specified -> Set min the smallest value and max to the largest value

* simplify logic, new ParseError & add tests

* simplify code according to the review comments

* address review comments

* more fine-grained tests