[mlir] Add support for detecting single use callables in the Inliner.

Summary: This is somewhat complex(annoying) as it involves directly tracking the uses within each of the callgraph nodes, and updating them as needed during inlining. The benefit of this is that we can have a more exact cost model, enable inlining some otherwise non-inlinable cases, and also ensure that newly dead callables are properly disposed of.

Differential Revision: https://reviews.llvm.org/D75476