Feature: disable or enable tls only or non-tls service ports only

[jessebot]

Description of the change

We currently create a certificate for you like this:
https://github.com/jessebot/coturn-chart/blob/3e770404a9482b4381e9296951a1a4164173fa18/charts/coturn/values.yaml#L43-L46

That's left over from the chart we forked. We don't even use that value in the two service templates we have 🤦 We should change that to tls.enabled and allow for an tls.existingSecret. When tls.enabled is true, we should maybe not allow any unencrypted traffic, so we should not create the unencrypted ports in the services here and here:

https://github.com/jessebot/coturn-chart/blob/3e770404a9482b4381e9296951a1a4164173fa18/charts/coturn/templates/service-tcp.yaml#L14-L20

https://github.com/jessebot/coturn-chart/blob/3e770404a9482b4381e9296951a1a4164173fa18/charts/coturn/templates/service-udp.yaml#L14-L20

Likewise if tls.enabled is false we should not create the tls ports and instead only create the ports above.

Benefits

This allows you to be completely secure... or not, without the weird in between, as right now, we create both tls and non-tls ports for both UDP/TCP services.

Possible drawbacks and Additional Comments

I suppose it might make sense to allow for both to be configured? Maybe we also need coturn.ports.tls.enabled and coturn.ports.insecure.enabled? 🤔 Open to better names for the values there.

Do we even need two services btw? Can we just have one? 🤷

[jessebot]

@cloudymax interested in your thoughts