Add queues for netlink messages

[awlx]

It adds a separate thread for the netlink processing and a FIFO queue.

This resolves #103

[awlx]

Example Debug output:

Sep 18 16:36:38 gw07 wgkex[16630]: 2023-09-18 16:36:38,817,817 DEBUG    [msg_queue.py:39] Queue is not empty current size is 11
Sep 18 16:36:38 gw07 wgkex[16630]: 2023-09-18 16:36:38,817,817 DEBUG    [msg_queue.py:41] Processing queue item dzz4r646646644=' for domain welt
Sep 18 16:36:38 gw07 wgkex[16630]: 2023-09-18 16:36:38,818,818 INFO     [msg_queue.py:47] Processing queue for key dzz4r646646644=' on domain welt with lladdr fe80::2b9:8aff:fea2:c111/128
Sep 18 16:36:38 gw07 wgkex[16630]: 2023-09-18 16:36:38,820,820 DEBUG    [netlink.py:100] Handling links for WireGuardClient(public_key='dzz4r646646644='', domain='welt', remove=False)
Sep 18 16:36:38 gw07 wgkex[16630]: 2023-09-18 16:36:38,924,924 INFO     [netlink.py:104] Updated route for WireGuardClient(public_key='dzz4r646646644=', domain='welt', remove=False)