feat: Migrate `.contains()` and `.shadow()` to queries

[BlueWinds]

What would you like?

As part of #7306, and building upon #23550, we're migrating additional commands to be queries. This PR is one part of that; It can be done piece-by-piece.

Why is this needed?

Queries don't suffer from Detached DOM errors. They are also significantly simpler to write and debug than commands - less code to maintain, and what code is there is more straightforward.

Other

No response