Add dummy deployment with token addresses

[nventuro]

It'd be handy to have a 'fake' deployment task we could reference to get the address of BAL and WETH, since we'll need this in multiple places.

This would just be the outputs, with no inputs, index, etc., meaning some of the automatic checks will fail. Maybe we can have a task prefix that is ignored by check-deployments and friends? e.g. 00000-tokens.