dev-server: Properly deal with IPv6

[mjameswh]

What was changed

• Correctly handle binding to --ip 0.0.0.0 on machines that have IPv6 support but isn't fully configured (e.g. doesn't have a loopback interface bound to ::1). Fix [Bug] dev server panics when binding to 0.0.0.0 in docker container #595.
• Allow binding to IPv6 (e.g. --ip ::1 or --ui-ip ::).
• Correctly honor values of arguments --ui-ip and --ui-port. Fix [Bug] cannot bind ui to different IP using--ui-ip #602.
• Gives proper error message in all cases where ip:port is already in use. Fix [Feature Request] Error when a port is taken #242.
• Correctly handle binding on addresses that do not encompass 127.0.0.1 (e.g. --ip 127.0.0.2).

How this was tested

I added a few integration tests.

However, most cases fixed in this PR relates to specific network configuration, which can't easily be reproduced in CI or on developer machines. These changes were therefore only validated by manual testing.

For future reference, this is the gist of what I did on my Mac.

# Add two more loopback IPs
sudo ifconfig lo0 alias 127.0.0.2 up
sudo ifconfig lo0 alias 127.0.0.3 up

# Make sure that loopback has IPv6
ifconfig lo0 | grep ::1

# Test various cases
./temporal server start-dev --port 7235 --ui-port 7236 --http-port 7237 --metrics-port 7238 --ip :: --ui-ip ::1
./temporal server start-dev --port 7235 --ui-port 7236 --http-port 7237 --metrics-port 7238 --ip 127.0.0.2 --ui-ip 127.0.0.3
./temporal server start-dev --port 7235 --ui-port 7236 --http-port 7237 --metrics-port 7238 --ip 0.0.0.0 --ui-ip 127.0.0.1

# For each of the preceeding commands, assert:

# 1. That ports were bounded correctly
lsof -n -p $( ps | grep "temporal[ ]server" | cut -f 1 -d " " ) | grep LISTEN

# 2. That UI interface opens without issue
# 3. The prometheus metrics page opens  without issue
# 4. No error in server logs

To test in Docker, I had to use Rancher Desktop, with Kubernetes support enabled. The important thing for testing #595 is that the kernel of the virtual machine used by Docker must be compiled with IPv6 support (e.g. /proc/sys/net/ipv6 exists), but the container image must not be configured for IPv6 (e.g. ip addr show dev lo doesn't show any IPv6 address, and ping6 ::1 fails). The VM used by Docker Desktop won't work, apparently because it configures container's IPv6 correctly.

[cretz]

Suggested change

	func MaybeEscapeIpv6(host string) string {
	func MaybeEscapeIPv6(host string) string {

(pedantic, I know)

[cretz]

My concern here is that we are not choosing a specific IP version based on the input string when binding, but we are when dialing. I am concerned about an ipv6-only machine (assuming they exist) if we blindly say --ip 0.0.0.0 works for all IP versions. But it's not a real issue, we can just tell people to pass in --ip :: or something.

[cretz]

How this was tested

Feel free to add those tests explicitly if it would help (though I only mean the tests for properly enabled IPv4/IPv6, obviously won't work for use cases where you want to test no-IPv6 loopback)