[catalog-server] Add schemas and specifications via values

[blootsvoets]

Use approach as sketched in helmfile feature request to have catalog-server read schemas and specifications from a dedicated directory, making it easier to add new schemas and specifications to an installation.

{{- range $_, $file := ( exec "sh" (list "-c" "echo -n path/to/files/*") | splitList " " ) }}
{{ regexReplaceAll ".*/" $file "" | indent 4 }}: |
{{ readFile $file | indent 6 }}
{{ end }}