A string reprenting a key in the key-value database. Key path components are split by a slash (e.g. a/b/c has the path components ["a", "b", "c"]). Slashes can be escaped by using a forward slash (e.g. a/b\/c/d has the path components ["a", "b/c", "d"]). See rivet.api.kv.common#KeyComponents for the structure of a rivet.api.kv.common#Key split by /.