The activated setup mode is indicated by the WLAN LED.

Co-authored-by: David Bauer <mail@david-bauer.net>

for devices in targets that do no implement `get_status_led` in /etc/diag.sh
and do not have an led-running in their dts

The package rebuild logic of OpenWrt only checks regular files. Avoid
symlinks in the files directory to make rebuilds more robust.

OpenWRT 19.07 enables urngd by default, so haveged is redundant.

With this commit, the status-led is set to be the "led-running"
device-tree alias for targets which do not implement the get_status_led
method in /etc/diag.sh.

Upstream commit 5eb7864a changed the method name for host-key
generation.

Some files have received some additional refactoring.

rpcd is not included in our images anymore since switching to gluon-web, so
we don't need to disable it anymore.

This allows to reach the node in setup mode over the same link-local IPv6
address as br-client uses during normal operation.

OpenWrt doesn't set the regdom unless a WLAN device is started. Explicitly set
the regdom in the setup mode to get the correct list of allowed txpower entries
in the planned LuCI module.

When an early reboot is triggered because an upgrade script has disabled the
config mode, we need to explicitly call /etc/init.d/done, otherwise the overlay
will not be finalized after a firstboot and we get an endless reboot loop.

Since switching to Barrier Breaker/procd, we'd not notice if we were
upgrading from a version before renaming the config file to gluon-setup-mode
as the upgrade scripts run after the preinit.

Fix this by checking later during setup mode init again and rebooting into the
regular run mode if we detect this case.