Pass task name to rocotorun to avoid erroneously running all tasks

[maddenp-cu]

Synopsis

• Pass the task name supplied by the uw rocoto iterate -t / --task option to rocotorun to prevent it from running all tasks when the named task does not exist.
• Factor strings out of uwtools.rocoto and into uwtools.strings.

For example, currently, using the AIGFS workflow as an example, running

$ uw rocoto iterate --cycle 2026-08-17T12 --database rocoto.db --workflow rocoto.xml --task foo

where no task named foo exists, results in

$ uw rocoto iterate --cycle 2026-08-17T12 --database rocoto.db --workflow rocoto.xml --task foo
[2026-08-18T02:29:36]     INFO Iterating workflow
[2026-08-18T02:30:07]     INFO Workflow status:
[2026-08-18T02:30:07]     INFO CYCLE                    TASK                       JOBID               STATE         EXIT STATUS     TRIES      DURATION
[2026-08-18T02:30:07]     INFO ================================================================================================================================
[2026-08-18T02:30:07]     INFO 202608170600                    prep    druby://10.212.21.11:44913          SUBMITTING                   -         0           0.0
[2026-08-18T02:30:07]     INFO 202608170600                forecast                           -                   -                   -         -             -
[2026-08-18T02:30:07]     INFO 202608170600                post_000                           -                   -                   -         -             -
...
[2026-08-18T02:30:07]     INFO 202608170600                post_120                           -                   -                   -         -             -
[2026-08-18T02:30:07]     INFO 202608170600                     all                           -                   -                   -         -             -

i.e. the prep task starts running. If it succeeds, further iteration will run the forecast task, etc. Although rocotorun has a -a / --all flag to request execution of all tasks, this seems to also be the default behavior when no task is specified, and uw rocoto iterate currently does not provide a task name.

This PR passes the -t <taskname> to rocotorun. This prevents Rocoto from executing anything when a bogus task name is provided, which is an improvement. I would prefer to detect that a bogus task name was provided and halt uw, but I have not found a way to do this: The Rocoto database does not even exist until rocotorun is called and, even then, the jobs table appears only to be populated with task information as tasks become eligible to run. Short of parsing the Rocoto XML ourselves -- and expanding metatask names, which seems risky -- this may be the best easy solution.

Type

• Bug fix (corrects a known issue)

Impact

• This is a non-breaking change (existing functionality continues to work as expected)

Checklist

• I have added myself and any co-authors to the PR's Assignees list.
• I have reviewed the documentation and have made any updates necessitated by this change.
• Where helpful, I have written comments in this PR's Files changed view to assist reviewers.