Backporting the MFP patch allows us to utilize WPA3 features on this
target.

Tested on TP-Link Archer C20i

Separate wireless-related helper methods from the util module to a
new wireless module. This keeps them separated, as the amount of
wireless helpers increased in the past, justifying a separate module.

- Use util.find_phy()
- Stop foreach() as soon as the result is known

gsub() returns the number of matches as its second return value. This
was unintendedly passed through by the util functions trim() and
node_id(). It can be presumed that this had no effect in practice, but
it can lead to surprising output when passing values to print() for
debugging.

Fixes commit 6692095f

This adds a helper method, which determines if the current platform
supports WPA3 or not.

WPA3 is supported if
 - the device is not in the featureset category "tiny"
 - the WiFi driver supports 802.11w management frame protection

Allow wildcard matches on all subtargets of a target, or a full wildcard
always returning true when no arguments are passed.

mac_to_ip() calculates an ipv6 address from a mac address according to
RFC 4291. For wireguard we have to use specially crafted addresses that
must be unique. This allows calculating such unique mac-based addresses
by allowing to optionally specifying the bytes to be inserted into the
address.

This package allows to automatically switch to another domain, either
at a given point in time or after the node was offline long enough.

Gluon has multiple ways to obtain unique MAC-addresses. They are either
provided by the WiFi driver or derived from the primary MAC-address.

Quoting the same file:

> It's necessary that the first 45 bits of the MAC address don't
> vary on a single hardware interface, since some chips are using
> a hardware MAC filter. (e.g 'rt305x')

This currently fails in case the rt35xx based chips mac address differs
from the primary MAC. In this case, the MAC address for the client0 radio
(vif 1) comes from the WiFi driver. As there is only a single
MAC-address provided by '/sys/class/ieee80211/phyX/addresses' but the
MAC-address for mesh 0 (vif 2) is derived from the Node-ID, resulting in
different first 45 bits. The WiFi won't come up altogether in this case.

This commit verifies at least 4 MAC-Addresses are provided by the WiFi
driver. If this is not the case, all MAC-addresses are derived from the
primary MAC. This way, affected radios are working correctly.

gluon-core, gluon-mesh-babel: move lua functions that generate ll-addresses from a mac into gluon-core

exec() is moved to gluon.util.

Both gluon.sysconfig and libgluonutil already remove the trailing newline
if it exists. It's nicer to avoid files without a trailing newline, e.g.
for printing the file contents in a terminal.

Allows to remove some redundant UCI lookups.

[Matthias Schiffer: rebase]

This should not convert JSON to a Lua table and back, as this loses the
distinction between arrays and objects, but as our site.conf is defined in
Lua anyways (for now), this can be fixed in a later revision.

[Matthias Schiffer: rename to gluon-show-site, rebase]

By basing the Lua gluon.site module on gluonutil_load_site_config(), the
config load implementation needs to changed only in a single place for
multi-domain support.

In particular, this affects users of gluon.util.iterate_radios.

The new gluon.site lua library will eventually replace gluon.site_config
(which is hereby deprecated, but will continue to be supported for a
while).

The new gluon.site library will wrap all values to allow traversing
non-existing tables without errors.

    site = require 'gluon.site'
    c = site.a.b.c -- doesn't fail even if a or a.b don't exist

The wrapped values must be unwrapped using call syntax:

    site_name = site.site_name()

Using the call syntax on a non-existing value will return nil. An
alternative default value may be passed instead:

    mac = site.next_node.mac('16:41:95:40:f7:dc')

While we use the hexadecimal representation as a hash input for simplicity,
it should not be interpreted as case-sensitive.