gluon-status-page-api: Switch from debugfs to batadv netlink

The batadv debugfs requires large memory blocks to write the text debug
tables. This is inefficient for large tables like the global translation
table or the originators table.

The memory requirement can be reduced by using netlink. It copies smaller
packets in a binary format to the userspace program. gluon-status-page-api
can therefore parse larger originator tables without causing an OOM on
systems which are tight on memory.

Signed-off-by: Sven Eckelmann <sven@narfation.org>