Remove the version directory from our reconcilers. (#3840)
Remove the version directory from our reconcilers. (#3840)

We had done this with an ignorance of how CRD versioning would work.  We now know this to be unnecessary and it's more typing.

This change is the result of the following commands:
```
sed -i 's@pkg/reconciler/v1alpha1@pkg/reconciler@g' $(find -name '*.go' | xargs grep 'pkg/reconciler/v1alpha1' | cut -d':' -f 1 | uniq)
git mv pkg/reconciler/v1alpha1/* pkg/reconciler/
for x in $(find pkg/reconciler -name '*.yaml'); do rm $x; ln -s -r config/$(basename $x) $x; done
```

I've also edited the paths in `hack/update-codegen.sh`.
knative-sandbox/net-istio,knative-sandbox/net-istio