Creat a proper CI so all targets are continually tested

[titzer]

Currently, testing Virgil development is manual with the aeneas test command, that will do best effort to run tests on as many supported execution platforms as the host provides. Usually that's enough coverage to have a JVM, a native target (one of x86[-64]-(darwin|linux)) and a Wasm engine (node/v8 or Wizard). A drawback is that, despite preliminary support for remote test targets, there isn't a full solution for all platforms.

With a continuous integration solution for each platform, then tests could run automatically on all platforms.