Add Gitaly command to remove a repository from the filesystem

Problem Statement

Based on &6723 (closed), it has been proposed to add a command to trigger a removal of a repository from a Gitaly Cluster filesystem as well as the Praefect tracking database. This can be used in events such as a failed Geo sync, where a repo needs to be entirely removed to be redownloaded and synced.

Problem Validation

Given the numerous customer requests documented on &6723 (closed), this problem has been realized by our customers and can therefore be considered validated.