Feature request: A dictionary of values for the commit message template

[matheuscscp]

It'd be really nice to be able to specify a map[string]string dictionary to be passed to the commit message template, e.g. .spec.git.commit.messageTemplateValues. This way I can use kustomize/helm to specify different values for different ImageUpdateAutomation objects using the same message template.

For example: cluster: prod, then use {{ index .Values "cluster" }} in the message template.