added go_router nav2 scenario implementations

added go_router nav2 scenario implementations

added vs code settings file to .gitignore

Pre-launch Checklist

[X] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
[X] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
[X] I read the [Flutter Style Guide] recently, and have followed its advice.
[X] I signed the [CLA].
[X] I listed at least one issue that this PR fixes in the description above.
[X] I updated/added relevant documentation (doc comments with ///).
[X] I added new tests to check the change I am making, or this PR is [test-exempt].
[X] All existing and new tests are passing.