Add new deprecated_insecure_accept_external_unencrypted_http_requests
value in values.yaml. Allow it to be a boolean or a string to make it
easier to use (both --data-value and --data-value-yaml will work).
Also:
- Consider "ip6-localhost" and "ip6-loopback" to be loopback addresses
for the validation
- Remove unused env.SupervisorHTTPAddress var
- Deprecate the `service_http_*` values in values.yaml by renaming them
and causing a ytt render error when the old names are used