Add helm chart override fields to `DevfileRegistry` registry operator CRD

[michael-valdron]

Which area/kind this issue is related to?

/area registry

Issue Description

Using the helm chart, one can use the following override parameters:

• hostnameOverride - overrides the entire ingress hostname and domain
• nameOverride - overrides the app name
• fullnameOverride - overrides the full app name

Hostname override example

helm install devfile-registry deploy/chart/devfile-registry ... --set hostnameOverride='dr.192.168.x.x.nip.io' ...

App name and full app name override example

helm install devfile-registry deploy/chart/devfile-registry ... --set nameOverride='dr' --set fullnameOverride='devfile-registry' ...

Acceptance Criteria

• Implement hostnameOverride field
• Implement nameOverride field
• Implement fullnameOverride field
• Create test case to set override fields
• Run integration tests to verify changes