* vpn support can be disabled (enabled by default), fixes #19107 (see trm_vpn option)
* vpn support can be limited to certain interfaces (see trm_vpnifacelist list option)
* openvpn support works now per instance (same as wireguard today)
* add an auto-login script for tplink-omada hotspots provided by Sebastian Muszynski <basti@linkt.de>
* remove pipefail command, see #19043 for reference

Signed-off-by: Dirk Brenken <dev@brenken.org>
(cherry picked from commit 963137dcc5)

* add wpa-supplicant package dependency
* removed no longer working 'db-bahn.login' and 'wifionice.login' auto-login scripts
* added the new 'wifibahn.login' script for auto-logins to captive portals WIFI@BAHN (DE),
  run tested on a single ICE (station logins are currently unsupported!)
* vodafone.login prepared to support free/time limited logins (still WIP!)
* change return code handling in login scripts and travelmate
* refine f_wifi function
* fix a few conercase issues

Signed-off-by: Dirk Brenken <dev@brenken.org>

* code cleanup
* add auto login script for Julianahoeve beach resort (NL)
* add auto login script for Vodafone hotspots (DE)
* add auto login script for telekom hotspots (DE)
* enhance captive portal detection to support html redirects as well
* change default captive portal detection url to
  'detectportal.firefox.com'

Signed-off-by: Dirk Brenken <dev@brenken.org>

* fix a vpn/iptables race condition
* remove needless dnsmasq dependency
* synchronize code-base of all auto-login scripts, due to
  COVID-19 restrictions all of them are still untested/WIP
* various small cleanups

Signed-off-by: Dirk Brenken <dev@brenken.org>

- new package dependency: curl (plus one of the wpad variants)
- optional package dependencies:
  - 'msmtp' for email notification support
  - 'wireguard' or 'openvpn' for vpn support
- removed WEP support, only WPA/WPA2/WPA3 are supported!
- new, more robust setup wizard (CLI and LuCI)
- more robust captive portal detection
- randomize mac addresses with every uplnk connect
- automatic vpn handling during uplink switch (only classic/simple
  client-setups for wireguard or openvpn are supported)
- email notifications after successful uplink connections
- automatically disable uplinks after n minutes, e.g. for timed
  connections
- automatically (re-)enable uplinks after n minutes, e.g. after failed
  login attempts
- complete LuCI rewrite - migrated to client side JS (separate PR)

Signed-off-by: Dirk Brenken <dev@brenken.org>