Add status to card loading

[obgibson]

Requirements for a pull request

• Unit tests related to the change have been updated
• Documentation related to the change has been updated

Description of the Change

Adds a status to the return value from the useTaskCards() hook so that the status can show in the UI.

Possible Drawbacks

More visual noise on the page.

Verification Process

• Load MFGUI
• Start a flow with a number of tasks (preferably slow)
• Navigate to a recently started task in MFGUI
• Note the "loading" indicators
• Note the card appearing

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• Bork your metaflow-service (e.g. by switching to a branch that doesn't support cards)
• Load MFGUI
• Start a flow with a number of tasks (preferably slow)
• Navigate to a recently started task in MFGUI
• Note the "loading" indicators
• Note the card timeout message

Release Notes

Shows status when loading cards