[RFE] PDB for console operands to avoid going too many replicas down

During master nodes upgrade when nodes are getting drained there's currently no protection from two or more operands going down. If your component is required to be available during upgrade or other voluntary disruptions, please consider deploying PDB to protect your operands.

The effort is tracked in https://issues.redhat.com/browse/WRKLDS-293.

Example:

• https://github.com/openshift/cluster-authentication-operator/pull/476/files

• https://github.com/openshift/cluster-authentication-operator/pull/514/files

Acceptance Criteria:
1. Create PDB controller in console-operator for both console and downloads pods
2. Add e2e tests for PDB in single node and multi node cluster

Note: We should consider to backport this to 4.10