enterprise.splunk.com/v1alpha1 resources spec is too generic

```apiVersion: enterprise.splunk.com/v1alpha1
kind: SplunkEnterprise
metadata:
  name: example
spec:
  resources:
    ...
```

This spec is mostly generic and not per instance type. I need different sizing for indexers, search-heads, spark workers and ICMs.

For example, I would like

```splunkCpuRequest```

to be split up into ```
indexerCpuRequest
searchHeadCpuRequest```
etc.
