(core) Fix undo error for automatically removed rows, especially in summary tables

Summary:
Fixes a bug noted here: https://grist.slack.com/archives/C069RUP71/p1662564341132349

This bug could happen quite easily as follows:

1. Have a formula in a summary table such as `$group.amount`. Typically there's also a `SUM` but that's not essential.
2. Find a group with nonzero values of `amount`.
3. Delete all rows in that group in the source table. Typically that just means one row in a lonely group.
4. The summary table row is automatically deleted.
5. Try to undo. This raises an error about trying to update a non-existent summary table row.

I tried to account for this undo problem in https://phab.getgrist.com/D3489 by not saving the updated value for `$group` when it was found to be empty. The reason this was insufficient is that `$group.amount` is immediately invalidated anyway when the source row(s) are deleted (I think because that's just how dependency relations involving references work) *and* the calculated value of `$group.amount` changes even if `$group` doesn't. For example, `$group.amount` may have previously been `[100, 200]`. After deleting the rows, `$group.amount` becomes `[0, 0]`. Keeping `$group` unchanged prevents `$group.amount` from just being `[]`, but deleting the source rows means that the amounts become the numeric default `0` which is still a change. This change in value is then noted which leads to saving an undo action to update the summary table record. All this happens in step 3 above, and the summary record is only deleted after that point.

This diff removes that special handling for `group` and instead adds a more general fix to `action_summary.py`. This inserts undo actions for deleted rows at the beginning of the undo list rather than at the end, which was already done for deleted tables and columns.

Test Plan: Python tests

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D3626

sandbox/grist/engine.py

@@ -826,11 +826,6 @@ class Engine(object):
           # know, so it can set the cell value appropriately and do some other bookkeeping.
           cycle = required and (node, row_id) in self._locked_cells
           value = self._recompute_one_cell(table, col, row_id, cycle=cycle, node=node)
-        except table_module.EmptySummaryRow:
-          # This record is going to be deleted after the update loop completes.
-          # Don't save a value for it because that will lead to broken undo actions
-          # trying to update a record that doesn't exist.
-          save_value = False
         except RequestingError:
           # The formula will be evaluated again soon when we have a response.
           save_value = False
@@ -956,9 +951,8 @@ class Engine(object):
         raise self._cell_required_error  # pylint: disable=raising-bad-type
       self.formula_tracer(col, record)
       return result
-    except (MemoryError, table_module.EmptySummaryRow):
+    except MemoryError:
       # Don't try to wrap memory errors.
-      # EmptySummaryRow should be handled in _recompute_step
       raise
     except:  # pylint: disable=bare-except
       # Since col.method runs untrusted user code, we use a bare except to catch all