message: rename `indy_collect_metrics` callback fields
diff: @@ -15,7 +15,7 @@ use libc::c_char;
  pub extern fn indy_collect_metrics(command_handle: CommandHandle,
  cb: Option<extern fn(command_handle_: CommandHandle,
  err: ErrorCode,
  - key: *const c_char)>) -> ErrorCode {
  + metrics_json: *const c_char)>) -> ErrorCode {
  trace!("indy_collect_metrics: >>> command_handle: {:?}, cb: {:?}",
  command_handle, cb);
  