add end-to-end backend flow for DSLX examples

It would be nice to have a non trivial example (like #994 or #995) that demonstate end-to-end backed flow with synthesis + pnr + sta + gds streaming based on https://github.com/hdl/bazel_rules_hdl.

Ideally we would show timing estimate for with modern research-y process node like https://github.com/The-OpenROAD-Project/asap7 and https://github.com/The-OpenROAD-Project/asap5.

It would be also nice if the flow as compatible with manufactuable https://github.com/google/open-source-pdks.