Fixes #1959

Provide the number of OWE stations in addition to the number of all
connected wireless clients.

This allows a user to enable WPA3-Personal and WPA2-WPA3-MM for the
private WiFi in case it is supported by the platform.

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

If WPA3 is not selected as a feature, autmatically include
hostapd-mini.

The gluon-wireless-encryption package selects a WPA3 supporting
hostapd package as a dependency and stores the information, which
encryption method is supported to the device.

This package adds support for SAE on 802.11s mesh connections.

Enabling this package will require all 802.11s mesh connections
to be encrypted using the SAE key agreement scheme. The security
of SAE relies upon the authentication through a shared secret.

In the context of public mesh networks a shared secret is an
obvious oxymoron. Still this functionality provides an improvement
over unencrypted mesh connections in that it protects against a
passive attacker who did not observe the key agreement. In addition
Management Frame Protection (802.11w) gets automatically enabled on
mesh interfaces to prevent protocol-level deauthentication attacks.

If `wifi.mesh.sae` is enabled a shared secret will automatically be
derived from the `prefix6` variable. This is as secure as it gets
for a public mesh network.

For *private* mesh networks `wifi.mesh.sae_passphrase` should be
set to your shared secret.

Fixes #1636

Remove a lot of redundant code by switching to a match table listing
the targets and boards for each candidate for the primary MAC interface.

In addition, we add some flexiblity by allow to switch out the sysfs file
data source for the MAC address.

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

Specification:
- MediaTek MT7620A (580 Mhz)
- 64 MB of RAM
- 8 MB of FLASH
- 2T2R 2.4 GHz and 1T1R 5 GHz
- 5x 10/100 Mbps Ethernet
- 2x external, non-detachable antennas
- UART (J1) header on PCB (115200 8n1)
- 8x LED (GPIO-controlled*), 2x button, power input switch
- 1 x USB 2.0 port

This reverts commits
- caf2dd03.
- 07ebac6a
- 55eff45f

I accidentally pushed these commits as I had them lying around on a
dirty checkout I did testing on.

- Split into multiple files
- Avoid alloca()

In addition this PR contains:
- split of gluon-respondd provider into multiple source files
- minor additional cleanups in gluon-mesh-babel respondd provider
  (untested, as the babel respondd provider already doesn't compile prior
  to these changes...)

While we're at it, also slightly optimize proto_gluon_bat0_renew.

Adjust for changed libbabelhelper API.

We don't use anything else from luci-base anymore.

The code is slightly cleaned up to fix compiler warnings.