This introduces `role=button[name="Click me"][pressed]` attribute-style
role selector. It is only available under `env.PLAYWRIGHT_EXPERIMENTAL_FEATURES`.
Supported attributes:
- `role` is required, for example `role=button`;
- `name` is accessible name, supports matching operators and regular expressions:
`role=button[name=/Click(me)?/]`;
- `checked` boolean/mixed, for example `role=checkbox[checked=false]`;
- `selected` boolean, for example `role=option[selected]`;
- `expanded` boolean, for example `role=button[expanded=true]`;
- `disabled` boolean, for example `role=button[disabled]`;
- `level` number, for example `role=heading[level=3]`;
- `pressed` boolean/mixed, for example `role=button[pressed="mixed"]`;
- `includeHidden` - by default, only non-hidden elements are considered.
Passing `role=button[includeHidden]` matches hidden elements as well.
