lease-checker: add options mechanism
lease-checker: add options mechanism

Previously, the user had to provide the exact target size of the ring. With options, we can also support target ranges.

scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris