Filesize captured at the index step can be stale at the time of transfer

[jackleland]

We probably want to update the filesize in the catalog after upload in case it changed in the interim, which happened to me when I uploaded a local log file. We could piggy back the catalog checksum update (#74) on this catalog update too, solving both problems at once

[nmassey001]

We should add an early failure on transfer to object store, if the file has changed size since the indexing.