Add FPortal

[Pante]

Describe the changes Add FPortal. This will be used for widgets such as tooltip and popover.

Checklist

• [x] I have read the CONTRIBUTING.md.
• [x] I have included the relevant unit/golden tests.
• [x] I have included the relevant samples.
• [x] I have updated the documentation accordingly.
• [x] I have updated the CHANGELOG.md if necessary.

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