kfdef application name missing doesnt fail kfctl build

[moficodes]

kind: KfDef
metadata:
  namespace: kubeflow
spec:
  applications:
# other applications omitted
  - kustomizeConfig:
      repoRef:
        name: manifests
        path: stacks/ibm/application/spartakus
#    name: spartakus
  repos:
  - name: manifests
    uri: https://github.com/moficodes/manifests/archive/master.tar.gz
  version: master

The above kfdef builds fine. but apply would fail and the error message is completely unrelated.

ERRO[0001] Error evaluating kustomization manifest for : accumulating resources: accumulating resources from '../../../../common/spartakus/overlays/application': open /common/spartakus/overlays/application: no such file or directory  filename="kustomize/kustomize.go:155"
Error: failed to apply:  (kubeflow.error): Code 500 with message: kfApp Apply failed for kustomize:  (kubeflow.error): Code 500 with message: error evaluating kustomization manifest for : accumulating resources: accumulating resources from '../../../../common/spartakus/overlays/application': open /common/spartakus/overlays/application: no such file or directory

We should add a check for application name or infer name from path.

[moficodes]

cc @Tomcli

[moficodes]

/assign

[Tomcli]

Raise an error is better in this case because the user can also miss other fields.