Add document pip support

[davideberlein]

• Add support for detecting video element visibility in Document PiP
• Drop opacity check as the intersection observer is not triggered if an element changes opacity and the check is flawed anyway as opacity of parents isn't considered.
• Add toggle document pip button to examples/demo page.

Closes #1317

[changeset-bot]

🦋 Changeset detected

Latest commit: 233fbc2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
livekit-client	Minor

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[lukasIO]

This looks great, thank you @davideberlein !

For the demo page two small nits:
It would be nice if the pip toggle could keep track of it's current state (enabled vs disabled) and there are still some exceptions spewing in the console after popping out the window where some updates are still trying to render to the window.document directly instead of to the pip document.

[davideberlein]

ions spewing in the console after popping out the window where some updates are still trying to render to the window.document directly instead of to the pip document

Good finding there, I missed 2 spots which I added and cleaned up the rest.

[lukasIO]

looks good, excited to support this new possibility :)