Description of problem:
When ipv4/ipv6.enabled is not mentioned, rust automatically configures it as "enabled: false".
Full editing is reasonable, but it breaks the old behavior on RHEL 8, need to evaluate it.

Version-Release number of selected component (if applicable):
nmstate-2.1.1-0.alpha.20220519.437e4a9.el9.x86_64
DISTRO=RHEL-9.1.0-20220531.0

How reproducible:
100%

Steps to Reproduce:
1. echo "
interfaces:
  - name: veth0
    type: veth
    state: up
    ipv4:
      enabled: true
      dhcp: true
    ipv6:
      enabled: true
      dhcp: true
      autoconf: true
    veth:
      peer: veth0_ep
" | nmstatectl apply

# for example if I want to disable autoconf
2. echo "
interfaces:
- name: veth0
  type: veth
  state: up
  ipv6:
    autoconf: false
" | nmstatectl apply


Actual results:
After applied, nmstate reported OK and returned this state:
---
dns-resolver: {}
route-rules: {}
routes: {}
interfaces:
  - name: veth0
    type: veth
    state: up
    ipv6:
      enabled: false  # this option was appended automatically
      autoconf: false
ovs-db: {}


Expected results:
Like on RHEL 8, only change the explicitly mentioned options 



Additional info:
Some other similar actions that differ with nmstate python:
interfaces:
- name: veth0
  ipv6:
    enabled: true
    autoconf: false
=> "dhcp" is not mentioned but set to false automatically


interfaces:
- name: veth0
  ipv4:
    enabled: true
    auto-dns: false
=> [2022-06-01T21:24:00Z WARN  nmstate::nm::checkpoint] Timeout on waiting rollback
NmstateError: VerificationError: Verification failure: veth0.interface.ipv4.enabled desire 'true', current 'false'


Assume successfully changed auto-dns to false, then try applying:
interfaces:
- name: veth0
  ipv4:
    enabled: true
    dhcp: true
=> "auto-dns" will be changed to true again.