Application namespace hardcoded for Kubeflow

[bartoszmajsak]

Relates to #605

Kubeflow relies on env variables to wire Istio resources together. Namely USE_ISTIO=true will enable Istio-specific logic but it also needs ISTIO_GATEWAY set in a form of namespace/gateway-name. Currently this is hardcoded to opendatahub/odh-gateway, but we should be able to change namespame name based on DSCInitializationSpec.ApplicationName.

In the v1 plugin this is done by overwriting ossm.env cached file in the service-mesh overlay before kustomize applies manifests.

It is introduced in opendatahub-io/kubeflow#96, now in https://github.com/opendatahub-io/kubeflow/pull/172/files#diff-19e9e6ace6726a23c7e0ae0fe3cf34db0c15e47ef53e5ac9a25488d43a514b55

v2 could follow the same approach in the workbenches.go. Some other components like the dashboard are doing string replacements in files - this can be re-used.

[bartoszmajsak]

Fixed in 724837d