Rework and consolidate CI

[nyurik]

Rework CI to run tests locally using the VM-installed Postgres on all target platforms.

CI jobs

• Build release versions on Linux/Win/Mac and save build results as output artifacts
• In a separate VMs (Linux/Win/Mac)
  • use nyurik/action-setup-postgis to install postgis and run tests using the built artifacts
  • run cargo test on Linux only
  • copy built artifacts from the build step, and run tests using the release martin binary
  • package and publish if this is a release

Other changes

• Port some minor changes from the rewrite to porting easier
• minor cleanups
• remove all "expected" data files - too unstable to be usable