* Factor index out of Reconciler
Applying multiple Bindings to the same subject makes the reconciler more
complex, so split out the index handling.
* unexport contents of index.go
* Apply multiple bindings to the same subject
The affected files are actually copyright 2019-2020,
but boilerplate-check fails if this is used. See:
https://github.com/mattmoor/boilerplate-check/issues/22
Fixes https://github.com/knative/pkg/issues/1786
This PR adds facilities to make it easier to create both components of a Binding
over "Pod Spec"-able resources. Rather than rehashing it all here, please look
at `./pkg/webhook/psbinding/README.md` for more details.