prometheus-node-exporter-lua: wifi_stations: add tx_failures & tx_retries metrics

[robertfoss]

Maintainer: @champtar Compile tested: WIP Run tested: WIP

Description: Submit the tx_retries & tx_failures stats that already are collected by iwinfo.

[PolynomialDivision]

You are missing a signed-off line in your commit message. Further you need to increase the pkg release.

[champtar]

I'm running an old 22.03 snapshot, but tx_retries & tx_failures are not present for me (i'm using wpad-wolfssl)

# lua
Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio (double int32)
> require "iwinfo"
> ifname = "wlan0"
> iw = iwinfo[iwinfo.type(ifname)]
> assoclist = iw.assoclist(ifname)
> for mac, station in pairs(assoclist) do
>> print(station.tx_retries)
>> end 
nil
nil
nil
nil

I see it in iwinfo code, no typos https://git.openwrt.org/?p=project/iwinfo.git;a=blob;f=iwinfo_nl80211.c;h=adb8c45f8fac4a2486010d987ef47a4922b671f4;hb=HEAD#l2169

I'll just add some if

[champtar]

I see tx_failed in the code, not tx_failures https://git.openwrt.org/?p=project/iwinfo.git;a=blob;f=iwinfo_nl80211.c;h=adb8c45f8fac4a2486010d987ef47a4922b671f4;hb=HEAD#l2172 Was this ever run tested ? (I see it marked as WIP)