Use op.operation.name to detect funcOps in tt-explorer

[vwellsTT]

Problem description

In previous PR, I was not properly checking for funcOps to avoid extraneous node in tt-explorer (because op.name will yield actual func name, op.operation.name will yield expected "func.func"). This is trivial fix to correct this logic, plus simplify call structure a bit based on Vraj's feedback

What's changed

Inlined one of the funcs I created, since it is only invoked once anyway + didn't add much clarity. Replaced relevant comparisons to "func.func" with op.operation.name instead of op.name

Checklist

• New/Existing tests provide coverage for changes
• Manually confirmed this eleminates bad nodes in tt-explorer

[vwellsTT]

this was wrong before, we do want to process operands on func ops, only want to avoid emitting a node for them (which is governed by other check, not this one). Otherwise, inputs arguments don't get nodes -> missing a lot of edges.