[video_player] Add Fullscreen for Web

[rsegecin]

Adds a feature on the video_player package to enable a video to go fullscreen on web platform.

flutter/flutter#64397

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages repo does use dart format.)
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I listed at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[stuartmorgan-g]

Thanks for the submission!

In the future, please do not delete the checklist that is in the PR template; it is there for a reason. This PR is missing required elements described in the checklist (I’ve restored it to the PR description), which need to be addressed before it moves forward with review.

I am marking the PR as a Draft. Please review the checklist, updating the PR as appropriate, and when that’s complete please feel free to mark the PR as ready for review.

[rsegecin]

Thanks for the submission!

In the future, please do not delete the checklist that is in the PR template; it is there for a reason. This PR is missing required elements described in the checklist (I’ve restored it to the PR description), which need to be addressed before it moves forward with review.

I am marking the PR as a Draft. Please review the checklist, updating the PR as appropriate, and when that’s complete please feel free to mark the PR as ready for review.

I'm sorry. It's my first pull, when I was creating I've checked the checklist by excluding it's items. I'm trying to get help on discord because I'm unsure about the package versioning, whether I should left as publish_to: none I've read this doc and I think I did it right and it's all good. If I missed something else please let me know, I think this feature will really be very beneficial to all flutter web projects.

[stuartmorgan-g]

• All existing and new tests are passing.

CI is showing many failures. Have you read https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#changing-federated-plugins ?

[rsegecin]

• All existing and new tests are passing.

CI is showing many failures. Have you read https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#changing-federated-plugins ?

I can see now, I think I'm closing this pull request and submitting a new one then. Thank you.