Converts an ID to the signed long integer representation used internally.
- requestType is longConvert
- id is a numerical ID, in decimal form but equivalent to an 8-byte unsigned integer as produced by SHA-256 hashing
- stringId (S) is the numerical ID
- longId (S) is the signed long integer (8-bytes) representation of the ID used internally, returned as a string
- requestProcessingTime (N) is the API request processing time (in millisec)