Add offline support to <ShowBase> and <Show>

[djhi]

Problem

Our components and hooks can't leverage the offline support provided by Tanstack Query.

Solution

• Make sure our data loading hooks returns the data needed to detect those cases
• Provide components, hooks and props allowing to handle offline scenarios
• Provide default offline components in ra-ui-materialui

How To Test

• <ShowBase>
• <IsOffline>
• <Show>
• <Offline>
• Tests

Additional Checks

• The PR targets master for a bugfix or a documentation fix, or next for a feature
• The PR includes unit tests (if not possible, describe why)
• The PR includes one or several stories (if not possible, describe why)
• The documentation is up to date

Also, please make sure to read the contributing guidelines.