Adding support to dynamic value in values.yaml

First of all this project is amazing!

I encountered an issue when i tried to use this chart as an dependency to my chart.

in my use case i want to be able to give a dynamic value in values yaml.
for an example i want that the configmap name to be dynamic because i want to deploy multiple solr cluters in the same k8s envirement.
my chart `values.yaml`
```yaml
global:
configmap: idolaman

solr:
podOptions:
volumes:
- name: my-configmap
source:
configMap:
name: "{{ .Values.global.configmap }}"

...
```
my Chart.yaml

```yaml
name: idolaman-solr
dependencies:
- name: solr
....
```

an solution might be change the `solr` chart to evaluate using tpl every value it gets

Start with the dependency values.yaml and Chart.yaml examples, then locate the solr chart templates that consume podOptions. Check how Helm's tpl evaluation applies to the ConfigMap name and test the dependency use case with multiple Solr clusters; done means the global.configmap expression resolves to the configured name.

Written by the indexing model from the issue text.