Add actions for building and testing (#8)

* Add a Github action for building and testing

On Windows, -- -//third_party/... doesn't seem to work, so add all test directories manually. Also run the tests_*. We run only fastbuild tests here, since the opt tests will be run in the release workflow.

Also fix a number of compilation and test issues found along the way.

.gitignore

@@ -11,3 +11,4 @@ dependencies
 *.includes
 .qtc_clangd
 bazel-*
+user.bazelrc