Add --https-bind for HTTPS-only connections on a different port

[scaleoutsean]

It's not a strong use case, but since I was asked to share it, I'll register it.

Use case:
If HTTPS port can be made available on a different port at the same time:

• InfluxDB 3 clients can choose the port/protocol that suits their needs
• No need to deal with the various burdens of workarounds such as reverse proxies to accommodate the "other" protocol
• Less guesswork for developers and users. The fact that one is using the wrong protocol isn't difficult to spot, but it's harder and more annoying to do that from clients such as Grafana.

Proposal:

• Allow both --http-bind and --https-bind for convenience and choice
• I have no opinion on how --https-bind should behave if --tls-* args or ENV vars aren't available (ignore, generate self-signed, etc.)

Current behaviour:
As described in the documentation, client has to know what to use at given port - HTTP or HTTPS - and all clients must pick whatever is offered.
If HTTP is selected because not all clients can use HTTPS, that's one extreme. If HTTPS is selected for everyone's good, older (e.g. TLS v1.1) clients may not be able to access InfluxDB even when all they do is just make simple non-mission critical read-only queries.

Desired behaviour:
Clients can choose to connect without or with TLS encryption if the server offers both.

Alternatives considered:
Currently there's no alternative to using whichever protocol is in place (HTTP or HTTPS) cluster-wide, so I guess the only way is to stand up and maintain a separate reverse proxy which isn't insignificant (cost, performance, maintenance, etc.).