Fixes #32161

This is @joelclimbsthings PR moved from woocommerce-admin repo.
This is the implementation of the reminder bar described in this issue. It will display on top of the header on a subset of pages, only when the task list is visible, and direct the user back to the task list.

Notes:

• This is currently manually assigned to use the task list with ID setup_experiment_1. We may need to add logic to this as we put together the experiment.
• I've currently got this functionality behind the tasklist-setup-experiment-1 feature flag, which will also be consolidated as we implement the experiment in another issue.
• This is added inside the preexisting <Header /> component to leverage the scroll and top margin logic that already existed.

Also note that I won't be around to merge or respond to feedback, so I'll need someone else to do so.

Screenshots

Detailed test instructions:

• Checkout branch on a fresh site (if your store is > 4 weeks old it will automatically hide the reminder bar)
• Enable the tasklist-setup-experiment-1 feature flag.
• Complete the OBW
• Complete a single step of the primary task list.
• You should not see the reminder bar on the Homescreen or any other page related to the tasks. You should see it everywhere else.
• Go to a non-task related page, such as Orders, and you should see the bar appear above the header. Ensure the copy starts with "You're doing great!"
• Click the link, which should redirect you to the Homescreen.
• Complete all but one task remaining.
• Go back to the Orders (or otherwise) page to view the reminder bar. It should appear similar but have different copy, starting with "Almost there."
• Click the link again to ensure that it returns you to the homescreen.
• Hide the list by clicking the ..' menu, and then return to the Orders page. The bar should now not be displayed.
• Re-enable task list by going to Orders->Help->Setup Wizard->Task List -> Enable.
• The reminder bar should now reappear when viewing the Orders page.
• Complete the task list.
• The reminder bar will no longer display on the Orders page.