Enable processing .adb (Alpine-style APK package repository 'database' files)

[danielfdickinson]

Currently OpenWrt does not have plaintext package lists on their download servers (e.g. the equivalent of APKBUILD for Alpine) but does have packages.adb files which are APK (Alpine-based package manager) repository package 'database'. If these could be processed a regular OpenWrt contributor (like myself) vs. server admin could add the current version of OpenWrt (Openwrt-25.12) to the updater.

If this is considered a reasonable addition, I could work on a PR to add this (Alpine-style APK) support.

[AMDmi3]

Sure, but note that this would require Rust implementation as well as we're going to switch to it eventually.

[danielfdickinson]

Got it. It could be a while, but I've been meaning to use Rust soon anyway.