Fix: accept both task ID and task name in command line --task argument

[ddebenedittis]

Description

When running tasks from the command line, e.g.

python source/standalone/workflows/rl_games/train.py --task=Isaac-Cartpole-Direct-v0 --headless

the --task argument should be the task ID (which includes the version number).

However, if an invalid task ID is provided, the error message from Gymnasium suggests using a similar task name, not a task ID, which can be confusing.

This pull request introduces the ability to use either a task ID or a task name in the --task argument. If a task name is provided, the script will default to using the latest version of the environment and print a warning to notify the user:

/workspace/isaaclab/source/Gymnasium/gymnasium/envs/registration.py:527: UserWarning: WARN: Using the latest versioned environment `Isaac-Cartpole-Direct-v0` instead of the unversioned environment `Isaac-Cartpole-Direct`.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings