ospf: route per-interface CLI through ietf-ospf YANG

Convert the per-interface DEFUNs that have RFC 9129 leaf
counterparts to DEFPY_YANG, so operators typing the legacy
syntax at vtysh land on the same NB callbacks glang emits to.

Commands converted on each daemon:
  v2:  ip ospf cost / hello-interval / dead-interval /
       priority / mtu-ignore / passive + their `no` forms
       + the hidden `ospf X` aliases (cost, hello, priority,
       dead-interval, no_ospf_cost, no_ospf_hello_interval,
       no_ospf_dead_interval, no_ospf_priority)
  v3:  ipv6 ospf6 cost / hello-interval / dead-interval /
       priority / mtu-ignore / passive + their `no` forms

Conversion pattern:
  * v2 commands take an optional `[A.B.C.D]` per-address
    override that has no RFC 9129 representation. Each
    DEFPY_YANG body checks `if (!ifaddr_str && per_iface_xpath
    returns 0)` and dispatches through nb_cli_enqueue_change /
    nb_cli_apply_changes; on the negative path it falls back
    to the legacy direct-mutation logic, preserving the
    per-address-override capability for operators that need
    it.
  * The YANG path also requires the interface to be in an
    area (if_area on IF_DEF_PARAMS). Operators setting
    per-interface attrs on an unattached interface continue to
    use the legacy path -- the YANG model can't express
    "interface params before area assignment" because the
    leaves live under areas/area[id]/interfaces.
  * Per-leaf bodies factor into small `_apply` helpers shared
    by the main `ip ospf X` form and the hidden backwards-
    compat `ospf X` alias (v2 only).

Internal API:
  * ospfd/ospf_vty.c gains a new ospf_per_iface_xpath helper
    (mirrors ospf6d's ospf6_per_iface_xpath added in the same
    file pattern). Both check the same gating conditions:
    interface exists, has a VRF, ospf instance present,
    if_area / oi->area set.
  * v3's hello-interval / dead-interval / priority each lost
    their ALIAS-based dual-purpose DEFUN that handled both set
    and `no` via a runtime strmatch on argv[0]->text. Split
    into clean DEFPY_YANG pairs (set + no) which is both more
    readable and easier for vtysh to dispatch correctly.

Not converted (deferred):
  * `ip ospf retransmit-interval`, `ip ospf area`,
    `ip ospf network`, `ip ospf dead-interval minimal
    hello-multiplier` -- each has complications that make
    them their own follow-up slices (area instance-id
    conflicts, network FRR-specific dmvpn modifiers, fast-
    hello multiplier outside RFC 9129). All four continue to
    work via the legacy CLI direct-mutation path.

Test coverage:
  * test_ospf_per_iface_cli_routes_through_yang exercises all
    twelve converted set forms (six v2 + six v3) plus their
    `no` forms via vtysh on r1-eth1, confirms running-config
    reflects each change and clears it on the `no`. Drives
    the same NB callbacks that mgmt-set-config does, so it
    proves the dispatch goes through YANG even though the
    operator typed legacy syntax.

Signed-off-by: lamestllama <eric@eparsonage.com>

Author: lamestllama