Referring interface using SR-IOV PF name and VF ID

The SR-IOV VF interface name could be unpredictable due to complex naming rule of systemd/udev. To simplify the effort on referring the SR-IOV VF interface, with nmstate 2.2.0, we introduce the support of this special interface name format:

sriov:<pf_name>:<vf_id>

For example, to set MTU of VF 1 of PF eth1:

interfaces:
  - name: sriov:eth1:1
    type: ethernet
    state: up
    mtu: 1500

You may also use this naming format in bond, Linux bridge or OVS bridge as port name:

---
interfaces:
  - name: br0
    type: linux-bridge
    state: up
    bridge:
      port:
        - name: sriov:eth1:2

---
interfaces:
- name: bond99
  type: bond
  state: up
  link-aggregation:
    mode: balance-rr
    port:
    - sriov:eth1:1

---
interfaces:
  - name: br0
    type: ovs-bridge
    state: up
    bridge:
      port:
      - name: ovs0
      - name: sriov:eth1:1