integrate DDC inference with new task model

[jmesserly]

we need to replace LibraryResolverWithInference with a new design that fits into the task model. It should be possible, somewhat similar to how constants are computed. This unblocks the new task model

[vsmenon]

@bwilkerson and @leafpetersen have more or less done this. I'll close and open an new issue to track migrating ddc to the new task model code.