update(Tooltip): Render Popover's popup in Overlay component

[espressoroaster]

to: @williaster @alecklandgraf

Description

This PR refactors Popover to render inside an <Overlay> component, just like the plain tooltip. It also moves the popup mouseEnter and mouseLeave handlers up to the popup content's outermost div.

Note: We'll want to land #391 first, and then update the target of this PR to master. I set the base of this PR to the Overlay PR to facilitate code review.

Motivation and Context

The original Popover component rendered in a simple div with a style of zIndex:1. This was naive on my part for several reasons:

1. The Popover would need a much larger zIndex to escape divs with zIndexes potentially much larger than 1.
2. In our Popover-inside-DataTable use case, the Popover was unable to escape a DataTable row, while a regular Tooltip, which rendered in Overlay's portal, was able to.

Testing

Tested with existing unit tests and new story book story.

Screenshots

Checklist

• [x] My code follows the style guide of this project.
• [x] I have updated or added documentation accordingly.
• [x] I have read the CONTRIBUTING document.

[airbnb-bot]

Size Changes

Package	Diff	ESM	Prev ESM	CJS	Prev CJS
core	+0.0%	566.78 KB	566.56 KB	708.84 KB	708.61 KB

Compared to master. File sizes are unminified and ungzipped.

View raw build stats

Previous (master)

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Current

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  },
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  },
  "core": {
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    "lib": 725857
  },
  "forms": {
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    "lib": 49298
  },
  "icons": {
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    "lib": 205626
  },
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    "lib": 20770
  },
  "metrics": {
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    "lib": 7729
  },
  "test-utils": {
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    "lib": 5937
  }
}