Allow tagging target groups separately from ALB

[jan-ludvik]

Is your feature request related to a problem?
We have one ALB that combines many ingresses. I want to tag target groups with service tags, something like service=foo. I tried using alb.ingress.kubernetes.io/tags annotation but that doesn't work as controller will try to merge all these different service tags and fail. I think that's understandable for ALB itself but target group could still be tagged.

Describe the solution you'd like
A description of what you want to happen.
Ability to specify tags for target groups.

Describe alternatives you've considered
A description of any alternative solutions or features you've considered.
Lambda copying tags from ingress.k8s.aws/resource (which does have service name in it) to service tag and stripping extra parts of the string.
I want to use this in datadog to filter target groups by service but unfortunately datadog doesn't allow wildcards in dashboard variables. Even then tags on target groups seem reasonable to me.