[WIP] Show error message in the grid's body

[rogyar]

Description (*)

This PR introduces a flow for showing error message in the assets grid body

Fixed Issues (if relevant)

1. Display connection errors in the grid body #466 : Display connection errors in the grid body

Manual testing scenarios (*)

1. Login to admin panel
2. Provide incorrect API key in configuration (Stores -> Configuration -> System -> Adobe Stock) Integration fieldset
3. Open Magento Media Gallery (i.e. go to Cms -> Pages, edit the page and insert image)
4. Click "Search Adobe Stock" button to open images grid

The error message is being shown in the grid body.

[ghost]

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