Description of problem:
When set routing rules like "ip-from: 24.4.4.4/24", it will report error:
  File "/usr/lib64/python3.6/ipaddress.py", line 1519, in __init__
    raise ValueError('%s has host bits set' % self)
ValueError: 24.4.4.4/24 has host bits set
Please do it like what route-config does, to convert it to 24.4.4.0/24 according to subnet mask automatically.

Version-Release number of selected component (if applicable):
nmstate-0.2.6-4.8.el8.noarch
NetworkManager-1.22.8-4.el8.x86_64
DISTRO=RHEL-8.2.0-20200319.n.1
Linux hp-dl388g8-04.rhts.eng.pek2.redhat.com 4.18.0-190.el8.x86_64 #1 SMP Wed Mar 18 09:34:40 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

How reproducible:
100%

Steps to Reproduce:
1.# cat veth0-route.yaml 
---
interfaces:
  - name: veth0
    type: ethernet
    state: up
    ipv4:
      address:
      - ip: 4.4.4.4
        prefix-length: 24
      enabled: true
route-rules:
  config:
  - ip-to: 14.4.4.4/24
    priority: 4
    route-table: 4
  - ip-from: 24.4.4.4/24
    priority: 4
    route-table: 4
routes:
  config:
  - destination: 34.4.4.4/24
    metric: 4
    next-hop-address: 4.4.4.1
    next-hop-interface: veth0
    table-id: 4

2. nmstatectl set veth0-route.yaml
3.

Actual results:
Traceback (most recent call last):
  File "/usr/bin/nmstatectl", line 11, in <module>
    load_entry_point('nmstate==0.2.6', 'console_scripts', 'nmstatectl')()
  File "/usr/lib/python3.6/site-packages/nmstatectl/nmstatectl.py", line 59, in main
    return args.func(args)
  File "/usr/lib/python3.6/site-packages/nmstatectl/nmstatectl.py", line 217, in apply
    statedata, args.verify, args.commit, args.timeout
  File "/usr/lib/python3.6/site-packages/nmstatectl/nmstatectl.py", line 241, in apply_state
    rollback_timeout=timeout,
  File "/usr/lib/python3.6/site-packages/libnmstate/deprecation.py", line 40, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/libnmstate/nm/nmclient.py", line 98, in wrapped
    ret = func(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/libnmstate/netapplier.py", line 70, in apply
    state.State(desired_state), verify_change, commit, rollback_timeout
  File "/usr/lib/python3.6/site-packages/libnmstate/netapplier.py", line 156, in _apply_ifaces_state
    state2edit, original_desired_state
  File "/usr/lib/python3.6/site-packages/libnmstate/netapplier.py", line 249, in _edit_interfaces
    iface2prepare + proxy_ifaces, original_desired_state
  File "/usr/lib/python3.6/site-packages/libnmstate/nm/applier.py", line 124, in prepare_edited_ifaces_configuration
    original_desired_iface_state=original_desired_iface_state,
  File "/usr/lib/python3.6/site-packages/libnmstate/nm/applier.py", line 404, in _build_connection_profile
    iface_desired_state.get(Interface.IPV4), base_profile
  File "/usr/lib/python3.6/site-packages/libnmstate/nm/ipv4.py", line 85, in create_setting
    config.get(nm_route.ROUTE_RULES_METADATA, []),
  File "/usr/lib/python3.6/site-packages/libnmstate/nm/route.py", line 262, in add_route_rules
    setting_ip.add_routing_rule(_rule_info_to_nm_rule(rule, family))
  File "/usr/lib/python3.6/site-packages/libnmstate/nm/route.py", line 275, in _rule_info_to_nm_rule
    nm_rule.set_from(*iplib.ip_address_full_to_tuple(ip_from))
  File "/usr/lib/python3.6/site-packages/libnmstate/iplib.py", line 50, in ip_address_full_to_tuple
    net = ipaddress.ip_network(addr)
  File "/usr/lib64/python3.6/ipaddress.py", line 74, in ip_network
    return IPv4Network(address, strict)
  File "/usr/lib64/python3.6/ipaddress.py", line 1519, in __init__
    raise ValueError('%s has host bits set' % self)
ValueError: 24.4.4.4/24 has host bits set

Expected results:
Success

Additional info:
nmcli and iproute2 util can deal with it well:
nmcli ipv4> set routing-rules priority 1000 to 100.1.1.1/24 table 50, priority 1001 from 100.9.9.9/24 table 50
nmcli ipv4> save
Connection 'dummy0' (f18985b8-0c57-42d8-b115-993b5d9bbc10) successfully updated.
[19:09:12@hp-dl388g8-04 ~]1# nmcli connection up dummy0
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/896)
[19:09:14@hp-dl388g8-04 ~]0# ip rule | grep 100
1000:	from all to 100.1.1.1/24 lookup 50
1001:	from 100.9.9.9/24 lookup 50
[19:09:22@hp-dl388g8-04 ~]0# ip route get 100.1.1.3
100.1.1.3 via 192.0.2.1 dev dummy0 table 50 src 192.0.2.251 uid 0 
    cache