These changes port the downstream codegen testing actions from
https://github.com/pulumi/pulumi-terraform-bridge to this repository.
`github.com/pulumi/pulumi/pkg/v2` is replaced with the PR HEAD.
These tests are only triggered on changes to `pkg/codegen` and
the workflow definition itself.
The windows release was appveyor calling a specific build target when
a tag was present. This is now called on a push to any of the branches
in the push category
This means it will not trigger on the pushes to the PR builds