Fix logic for ipv6 connections in is_port_available

[jdetter]

Description of Changes

• Small fix for checking to see if a port is available on some given interface.

updated:

The original implementation here used bind to try to discover if a port is currently in use. This isn't reliable due to platform differences - especially on windows where it's apparently acceptable to have a service running on both 0.0.0.0:3000 and 127.0.0.1:3000. This would cause bind to return successfully when we wanted it to fail. Also: binding on an ipv6 interface when a machine doesn't have ipv6 enabled caused random errors and it was too unreliable to be useful.

This new implementation uses get_socket_info which returns info on all sockets in use on the system. We can then look through this list to find services which conflict with our requested port.

updated 1/14:

This PR now includes a fix for flaky CLI tests. Originally we were using find_free_port to pick a random free port, but that was causing a race condition which resulted in test flakes. This PR fixes this issue by using 127.0.0.1:0 as the listen addr so the kernel will automatically pick a free port for us.

API and ABI breaking changes

None

Expected complexity level and risk

1 - this is a pretty isolated check, unlikely to introduce larger issues.

Testing

I tested on macos, windows and linux:

ALLOW
docusaurus is already running on   127.0.0.1:3000
SpacetimeDB then tries to start on 192.168.1.10:3000

ALLOW
docusaurus is already running on   ::1:3000
SpacetimeDB then tries to start on 192.168.1.10:3000

DENY
docusaurus is already running on   ::1:3000
SpacetimeDB then tries to start on 127.0.0.1:3000

DENY
docusaurus is already running on   0:0:0:0:0:0:0:0:3000
SpacetimeDB then tries to start on 0.0.0.0:3000

DENY
docusaurus is already running on   0:0:0:0:0:0:0:0:3000
SpacetimeDB then tries to start on 127.0.0.1:3000

DENY
docusaurus is already running on   0:0:0:0:0:0:0:0:3000
SpacetimeDB then tries to start on 192.168.1.10:3000

DENY
docusaurus is already running on   127.0.0.1:3000
SpacetimeDB then tries to start on 0:0:0:0:0:0:0:0:3000

DENY
docusaurus is already running on   192.168.1.10:3000
SpacetimeDB then tries to start on 0:0:0:0:0:0:0:0:3000

[jdetter]

This grabs the socket info from the kernel instead of manually trying to bind to the port on the ipv4/ipv6 interfaces.