@container rules should support not without parentheses

[devongovett]

See https://github.com/w3c/csswg-drafts/issues/7203#issuecomment-1183737711

The grammar in the spec requires that not be treated as part of the container condition rather than as part of the name, and parentheses are not required. This updates one previous test that was incorrect, and adds a new one. A new helper was necessary because test_query_valid also adds a second rule with more complex logic that wouldn't work in this case.

[yisibl]

cc @andruud