Refactor BuildSpecific to pass in the full qualified name

[vmchale]

Right now, the test suite takes e.g. PortProductsSum_testBench as an argument to BuildSpecific. That makes it needlessly complicated to find the clash-manifest.json for a particular entity (here, verilog/PortProductsSum.topEntity/clash-manifest.json).

We should pass in the full qualified name in BuildSpecific so that we can adroitly simulate with Vivado.