Various bugs in the Loop task

Describe the issue

The "Loop" task is still too immature :/ :

• Lack of information on ongoing executions (only successful ones are shown; nothing else). It would be good to see failed, running, and queued tasks at a minimum.
• As soon as a Loop runs within an execution, the connection to the interface is quickly lost, requiring (too) frequent refreshes to get status updates ("Connection interrupted / We couldn't reach your Kestra instance. Make sure it's running, then refresh the page.").
• When an iteration fails, it becomes inaccessible and the logs do not display. You have to go back to the executions list to find any information.
• The progress percentage is unformatted ("64.58333333333334%").

Environment

• Kestra Version: 2.0.1