Multiple runs of 'pac pages upload' command after a change keeps uploading the same record

[amervitz]

When running pac pages upload --path <path> --modelVersion 2 multiple times after editing a file, it keeps uploading the same record even when it isn't modified.

Steps to reproduce:

1. Edit a content snippet on the file system
2. Run pac pages upload and the content snippet gets uploaded
3. Immediately run pac pages upload again and the same content snippet gets uploaded, again, even though it wasn't changed after the previous upload.

I would think the tool should be recalculating the checksum for any uploaded records and updating them in the manifest.yml file so it can intelligently determine whether a record needs to be uploaded the next time the command is run again.

[amervitz]

Closing in favor of reporting this as an issue, see #1103.