Fold a finished (loading cleared) timed load of c into
loadEwmaMs: start to its stamped end, on the registry clock that stamped
the start. Without an end stamp (a thunk that never calls onLoadSettled)
the load is timed to now() — the first moment it was observed finished.
Fold a finished (
loadingcleared) timed load ofcintoloadEwmaMs: start to its stamped end, on the registry clock that stamped the start. Without an end stamp (a thunk that never callsonLoadSettled) the load is timed tonow()— the first moment it was observed finished.