Grant cert-manager RBAC to use all policies by default

[erikgb]

This PR should make it a bit easier to use approver-policy with cert-manager. By default, it will now grant RBAC permissions to use all CertificateRequestPolicies.

Close #216

/cc @hawksight @inteon @SgtCoDFish

[cert-manager-prow]

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[inteon]

I think this might be something for a v2 of this component.
Also, I would rather just drop the RBAC logic.

[erikgb]

I think this might be something for a v2 of this component. Also, I would rather just drop the RBAC logic.

Could you elaborate? Especially on the last part. "RBAC logic"?

[inteon]

I think this might be something for a v2 of this component. Also, I would rather just drop the RBAC logic.

Could you elaborate? Especially on the last part. "RBAC logic"?

Instead of using RBAC to link CertificateRequests with CertificateRequestPolicies, we can use the .spec.selector instead.

[erikgb]

I think this might be something for a v2 of this component. Also, I would rather just drop the RBAC logic.

Could you elaborate? Especially on the last part. "RBAC logic"?

Instead of using RBAC to link CertificateRequests with CertificateRequestPolicies, we can use the .spec.selector instead.

But why did you create the referenced issue? The selector is already in use, but that connects the CertificateRequestPolicy to Issuers. Not to who created the CertificateRequest. AFAIK, RBAC isn't able to use selectors.