Add Safari speaker selection support

[fkwp]

With the next iteration of Apple OSes the Speaker Selection API is supported (https://developer.apple.com/documentation/safari-release-notes/safari-26-release-notes#WebRTC)

This PR adds support for it by:

• adding a isSafariSpeakerSelectionSupported helper function
• using that helper function in supportsSetSinkId

fixes https://github.com/livekit/client-sdk-js/issues/1568 at least for macOS. In contrast to https://webrtc.github.io/samples/src/content/devices/input-output/ this PR does not (yet) fix the issue on iOS26

[changeset-bot[bot]]

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Latest commit: cba9b74b320a877b40c91fc8facecd7287500a0d

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[CLAassistant]

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