R1:ebb7ca8cbdae

Convert Owners paths to application transactions

Summary:
Ref T8320. Fixes T8317. Fixes T2831. Fixes T8073. Fixes T7127.

There was a bug with this line:

for ($ii = 0; $ii < count($paths); $ii++) {

...because the array may be sparse if there have been deletes, so `count($paths)` might be 3, but the real keys could be `1`, `5` and `6`. I think this was the primary issue behind T7127.

The old Editor did a lot of work to try to validate paths. When a path failed to validate, it silently discarded it.