Allow specify custom pathType in ingress.paths

[tyranron]

Found the current setup not working okay out-of-the-box.

Having the following values:

ingress:
  enabled: yes
  hosts: ["my.domain.tld"]
  paths: ["/cockroach/"]

Returns 404 error on accessing http://my.domain.tld/cockroach/. I think this is due to Admin UI doesn't work OK under sub-path.

Editing the Ingress resource manually to have the following:

# ...
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /$1
# ...
        paths:
          - path: /cockroach/(.*)
            pathType: ImplementationSpecific
# ...

does solve the issue, and Admin UI opens OK.

Unfortunately, the pathType cannot be specified from the Helm values at the moment, which this PR tries to fix.