Put a journaled write back

Restores the rows one whole-catalog write moved, each to exactly what it held before (an explicit on or off, or inherit), and only where the write is still the last word on it: the row must read as the write left it (a turn-on left explicit on rows; a turn-off left provider rows off and the tool rows it converged at inherit) and no later write may have journaled the slug. Anything else was decided since and is skipped and counted, never clobbered. Rows are never deleted, so putting an earlier write back afterwards still finds them. A tool pinned now stays on and counts as skipped: putting a turn-on back never takes a pin away. Any other tool put back off drops its MCP pin; a tool put back on does not get its pin back, but pass the unpinned slugs the write answered with as repin and the answer names those that came back on. Only the id a whole-catalog write answered with (all-on:… or all-off:…) is accepted: other writers converge exceptions their journals do not record, so their state cannot be rebuilt exactly. The revert is journaled like any other write, under this request's id.