[pgadmin4] Add possibility to use template-strings inside values.yaml

[pmoscode]

Is your feature request related to a problem? Please describe.
When pgadmin4 Helm chart is a subchart in another chart, then there might be a extra ConfigMap / Secret which is created in the parent / a silbings chart.
For that case the name of the ConfigMap / Secret might be dynamically generated (ex. {{ .Release.Name }}-pgadmin-server-definitions).
In this case I would like to use this templated name in the values.yaml for "extraConfigmapMounts.[].configMap" or "extraSecretMounts.[].secret".

Describe the solution you'd like
Because this is a ordinary string ("extraConfigmapMounts.[].configMap" and "extraSecretMounts.[].secret"), the Helm internal "tpl" function can be used to resolve the value.

Describe alternatives you've considered
I don't know any simple alternatives, when there are dynamic values in the "values.yaml" file.

Additional context
none