add a flag in task Table to indicate that task was UPLOADED to S3

[belforte]

for tasks submitted w/o dry run, UPLOADED is a transient status, tasks get there after QUEUED and progress immediately to SUBMITTED and possibly other statuses.
This makes it difficult to tell from Client is task is ready to run crab preparelocal as discussed in dmwm/CRABClient#5371 (comment)

Desired behavior could be that when Uploader action is completed a flag is set in the DB and client checks that, keeping UPLOADED status as it was until a few months ago only for tasks "halted" for dry-run submission which wait for a crab proceed command in order to progress to SUBMITTED.

Consistently with
https://cmscrab.docs.cern.ch/crab-design/crab-task-state.html