ability to choose network interface for multiple connections

[mathieujobin]

when connecting to two network at the same time.

Expected:

• we should not see a warning
• it should automatically switch to netvfy1 when netvfy0 is taken

Even better:

• create an interface such as choosenname0

Actual:

• it currently display a warning/error

$ sudo netvfy-agent -c 2ndnet
[2020-06-08 13:33:00] tapcfg_log: Opening device 'netvfy0' failed, trying to find another one
[2020-06-08 13:33:00] connecting to the controller...
[2020-06-08 13:33:06] connected!
[2020-06-08 13:33:06] connecting to the virtual network...
[2020-06-08 13:33:12] connected!

• 2nd interface is currently called tap0

6: netvfy0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    inet 198.18.0.4/24 brd 198.18.0.255 scope global netvfy0
       valid_lft forever preferred_lft forever
8: tap0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    inet 198.18.0.2/24 brd 198.18.0.255 scope global tap0

3rd network becomes tap1

6: netvfy0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    inet 198.18.0.4/24 brd 198.18.0.255 scope global netvfy0
       valid_lft forever preferred_lft forever
8: tap0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    inet 198.18.0.2/24 brd 198.18.0.255 scope global tap0
       valid_lft forever preferred_lft forever
9: tap1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    inet 198.18.0.1/24 brd 198.18.0.255 scope global tap1
       valid_lft forever preferred_lft forever