Redo tooltip component

[david-crespo]

We have a bunch of minor gripes with it and it has some issues (like #594) that are not worth fixing if we're just going to rewrite it anyway. Default choice of library is floating-ui, the successor to Popper.

Use cases

• Extra info in field labels
• Explaining why a button is disabled (e.g., add disk and add network interface are disabled unless instance is stopped)
• Show full datetime on hover over human-formatted “time ago” timestamps

Criteria

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