Inliner: observe block weight, update schema and data

Inliner: observe block weight, update schema and data

Add block weight as observation. At first blush I suspect this will be
useful only when the jit has IBC data, and even then only in the root
method blocks.

We'll likely need to either build up better profile estimates for the
inliner or else just try and cope without it somehow.

Dump out block weight and the per-call profitability in the observation
schema and data. Among other things this lets us cross-validate how well
the ModelPolicy predictions match the abstract GLMNET models...