Add ability to specify port for ui service

[lkysow]

I followed the same pattern as for nodePort. This is generally useful for specifying load balancer ports and we have this option already for mesh gateways. This is also useful for running in Minikube because minikube tunnel will open up localhost:<port> and so you can have the Consul UI on localhost:8500 rather than localhost:80.

Taken from hashicorp/consul-helm#1062

How I've tested this PR:

• helm tests

How I expect reviewers to test this PR: code

Checklist:

• Bats tests added
• CHANGELOG entry added (HashiCorp engineers only, community PRs should not add a changelog entry)

[lkysow]

From @kschoche

Looks great! Given that you mentioned it's potentially helpful in minikube, could we update a doc as well somewhere pointing this out? No worries if not.

Our minikube guide uses minikube service consul-ui (https://learn.hashicorp.com/tutorials/consul/kubernetes-minikube?utm_source=consul.io&utm_medium=docs&utm_content=k8s&utm_term=mk#access-the-consul-ui) which is another way to do it so I don't think we need to update that guide.

minikube tunnel is nice if you hav multiple services but that's a unique use-case.

[kschoche]

Nice!

[sadjamz]

This'll be really useful (I think for the CLI too?) thanks Luke!