miniupnpd: Enable IPv6 leases file

[lantis1008]

📦 miniupnpd

Maintainer: N/A

Description:
Introduces the IPv6 Leases file by default. This file will display active IPv6 leases requested under the IPv6 PCP (Port Control Protocol) a.k.a IPv6 Pinholes.

miniupnpd must be compiled with ENABLE_UPNPPINHOLE set for this to take effect. This is taken care of currently by setting CONFIG_IPV6.
The lease file looks something like

Proto;ClientIP;ClientPort;RemoteIP;RemotePort;UID;Timestamp;Description

This PR does not take care of the Luci changes necessary to expose this extra data to the GUI.

---

🧪 Run Testing Details

• OpenWrt Version: Gargoyle 1.15.x (OpenWrt 24.10.5)
• OpenWrt Target/Subtarget: x86/x64
• OpenWrt Device: Generic x86

---

✅ Formalities

• I have reviewed the CONTRIBUTING.md file for detailed contributing guidelines.

If your PR contains a patch:

• It can be applied using git am
• It has been refreshed to avoid offsets, fuzzes, etc., using

  make package/<your-package>/refresh V=s

• It is structured in a way that it is potentially upstreamable
  _{(e.g., subject line, commit description, etc.)
  We must try to upstream patches to reduce maintenance burden.}

[Self-Hosting-Group]

Have you checked existing PRs?
https://redirect.github.com/openwrt/packages/pull/24988

[lantis1008]

Have you checked existing PRs? https://redirect.github.com/openwrt/packages/pull/24988

You let me know when your request is no longer in draft and passes all checks, and I’ll happily withdraw.
For now, I am acting on the request of forum members to upstream my patch from Gargoyle.

[lantis1008]

Replaced by #28313 due to need for feature branch.

[Self-Hosting-Group]

Note: Lease file is also used for UPnP IGDv2 IPv6 port maps