macOS: implementation of InformationIterator

[apettel]

This patch allows list_info() to be used on macOS.

example output of list_port_info:

Port name: cu.debug-console
 - System location: /dev/cu.debug-console
 - Friendly name: cu.debug-console
 - Description: Serial Device
 - Manufacturer: Unknown
 - Serial #: N/A
 - HW ID: macOS:cu.debug-console
 - VID: 0x0000 PID: 0x0000

Port name: cu.Bluetooth-Incoming-Port
 - System location: /dev/cu.Bluetooth-Incoming-Port
 - Friendly name: cu.Bluetooth-Incoming-Port
 - Description: Bluetooth Serial Device
 - Manufacturer: Unknown
 - Serial #: N/A
 - HW ID: macOS:cu.Bluetooth-Incoming-Port
 - VID: 0x0000 PID: 0x0000

Port name: cu.usbmodem5buspirate1
 - System location: /dev/cu.usbmodem5buspirate1
 - Friendly name: cu.usbmodem5buspirate1
 - Description: Bus Pirate 5
 - Manufacturer: Bus Pirate
 - Serial #: 5buspirate
 - HW ID: macOS:cu.usbmodem5buspirate1
 - VID: 0x1209 PID: 0x7331

Port name: cu.usbmodem5buspirate3
 - System location: /dev/cu.usbmodem5buspirate3
 - Friendly name: cu.usbmodem5buspirate3
 - Description: Bus Pirate 5
 - Manufacturer: Bus Pirate
 - Serial #: 5buspirate
 - HW ID: macOS:cu.usbmodem5buspirate3
 - VID: 0x1209 PID: 0x7331

[lachlanm-git]

I don't have a macOS device and find it hard to make useful commentary directly on this PR. However, I'd point out:

• This PR would close https://github.com/ZigEmbeddedGroup/serial/issues/8
• You could remove this entry in the README.md: https://github.com/ZigEmbeddedGroup/serial/blob/master/README.md?plain=1#L59. That would also close out https://github.com/ZigEmbeddedGroup/serial/issues/41