HHH-9342 HQL "x member of treat(y as Type).collection" fails to parse

See [HHH-9342](https://hibernate.atlassian.net/browse/HHH-9342).

I added a new construction "treatAsPath" in the grammar and used it in the "member of" rule. This solves the specific bug I found. However I’m pretty sure this new construction should be used at other places too.