Create a guest VLAN network with a host flag.

From the host:
 - A new flag is added to switch from guest vlan/no-vlan.
 - no-vlan runs the same network configuration as before.
 - vlan exposes just the one tap device to qemu.
 - The default is to not use it, but in the future the host could use
   capability_query to decide what to set as the default.

From the guest:
 - ip_link_add is replaced with a single setup_network binary
 - setup_network uses a flag as a signal for vlan/no-vlan
 - no-vlan has the same behavior as the previous network configuration
 - vlan configures the mobile and wifi vlans
 - using a network namespace is possible future work

Bug: 111320496
Test: Ran cf_x86_phone-userdebug with and without vlans on a host.
Change-Id: I47cf4e1b1c70a339218d24053f29ffbcf9887263
Merged-In: I47cf4e1b1c70a339218d24053f29ffbcf9887263