Add channel commitment type to openchannel hook

[maybeast]

As a plugin developer, I'd like to be able to selectively accept or reject incoming channel requests based on their commitment type (e.g., to only allow anchor channels). Currently, it is not possible for a plugin subscribed to openchannel hook to reliably determine the commitment type of an incoming channel request.

If that is not feasible, could you suggest an alternative method to achieve this, such as a configuration option to restrict accepted channel types?