Check that the CRD is up to date on each PR

[yersan]

The CRD must be generated when you need to deploy the Operator in your cluster. The make target to generate it is the following one:

(main): $ make manifests

The CRD is generated at wildfly-operator/config/crd/bases/wildfly.org_wildflyservers.yaml

(0.5.x): $ ./operator-sdk generate crds or $ make codegen

The CRD is generated at wildfly-operator/deploy/crds/wildfly.org_wildflyservers_crd.yaml

We have to ensure that the CRD is always up to date and fail to accept the PR in such a case. At first glance, it seems a custom GitHub action could do this kind of work.