- Fixes: 71296430fa -- which only set `SKIP_ARMBIAN_REPO=yes` when `rootfs` cli shortcut used
- GHA artifact pipelines are generic across all artifacts, and don't use the cli shortcuts
- instead, they use the `artifact` shortcut, with the `WHAT=rootfs` parameter
- so in GHA pipelines `SKIP_ARMBIAN_REPO=yes` was not taking effect
- rootfs artifact itself now enforces `SKIP_ARMBIAN_REPO` to be `yes` and makes it readonly
- also add `SKIP_ARMBIAN_REPO` to the general change-tracking for more clarity about configs and hooks etc
- add change tracking calls before/after generic artifact config adapter for even more clarity
- `NETWORKING_STACK` can be set to `none` (in config phase, pre-extensions) to not-add any networking extensions
- keep defaulting to systemd-networkd if BUILD_MINIMAL and NetworkManager otherwise
- fix typo in extension name
- add `NETWORKING_STACK` to change-tracking
