Drop v1alpha1 in DevWorkspace v0.11.0

[sleshchenko]

v1alpha1 was deprecated in DWO 0.8.0 in favor of v1alpha2,
At the time OpenShift 4.9 is coming it makes sense to fully drop v1alpha2 from DWO 0.10.0 release.

[JPinkney]

Looking into this more, it looks like this is a multi-step process.
According to the openshift docs we need to do a few things:

1. Set served: false in the DevWorkspace CRD PR
2. Update the devfile/api dependency so that we pull in the DevWorkspace CRD with served: false PR
3. Release DWO 0.10 with the updated v1alpha1 DevWorkspace CRD
4. Drop v1alpha1 DevWorkspace completely from the devfile/api
5. Drop v1alpha1 DevWorkspace completely from DWO
6. Remove the v1alpha1 CRD from the OLM Manifests

Then when we release 0.11 the v1alpha1 CRDs will be fully removed

[amisevsk]

This task is on hold until OpenShift console adopts v1alpha2 as a default. If we stop serving v1alpha1 at this point, the Web Terminal Operator will not function correctly.