Fix publications' track property initialization

[hiroshihorie]

The constructors of LocalTrackPublication and RemoteTrackPublication relied on setting the track property during initialization. However, because updateTrack() was an un-awaited async method, the track property was null immediately after construction, which caused confusion.

[Copilot]

Pull Request Overview

This PR fixes an initialization issue where the track property was null immediately after construction of LocalTrackPublication and RemoteTrackPublication objects due to un-awaited async updateTrack() calls.

• Modified the base TrackPublication constructor to accept and directly initialize the track parameter
• Extracted track listener attachment logic into a reusable private method
• Updated both LocalTrackPublication and RemoteTrackPublication to pass the track parameter to the parent constructor instead of calling updateTrack()

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/src/publication/track_publication.dart	Added track parameter to constructor and extracted listener attachment logic
lib/src/publication/remote.dart	Updated constructor to pass track to parent instead of calling updateTrack()
lib/src/publication/local.dart	Updated constructor to pass track to parent instead of calling updateTrack()

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[pitazzo]

hi @hiroshihorie
since this PR was merged, we're receiving always null tracks inside the remote's participant video publications. Did this introduce any change on how tracks should be received?