CSV Upload "Succeeds" when no result UUID's are valid and nothing is uploaded

[SRGDamia1]

In a file with a malformed result UUID header, no valid result UUID's are found. But a successful upload message is still returned because not-valid UUIDs are simply ignored: https://github.com/WikiWatershed/monitor-my-watershed/blob/fff01cd53d9fb7062bd278a1edcadb75beb833cf/src/dataloaderservices/views.py#L352-L357

This is very confusing to the user when a success message appears but no data is uploaded. A warning message should appear for each column that doesn't have a valid UUID and a failure message should appear if no data at all is accepted.

In the file screenshot below which triggered the problem, the colon is missing in the Result UUID: header.