Replace BBQ callback thunks with lambdas

The lambdas allows for better StrongPointer/RefBase safety by replacing explicit incStrong/decStrong calls with RAII. Captured StrongPointers are created using sp<T>::fromExisting which helps detect RefBase errors such as creating a StrongPointer from an already deleted RefBase object.

Bug: 361588984
Flag: EXEMPT refactor
Test: presubmits
Change-Id: I1a0c0df882ec2a3f91f857c446418f3fb51689c1