Add quick connect mode

Use `bssid` and `channel` fields of the config to store BSSID and channel of
the last AP successfulyl connected to.
These are stored with `*` prefix and as a negated value to distinguish
them from user-provided values.
When first connecting, check all configs for entries with BSSID and
channel specified and build initial conenct queue with these static
entries, bypassing the scan. If no successful connection is made, we go
back to scanning and building a new queue as before.

Signed-off-by: Deomid "rojer" Ryabkov <rojer@rojer.me>

mos.yml

@@ -34,7 +34,8 @@ config_schema:
   - ["wifi.sta.enable", "b", {title: "Connect to existing WiFi"}]
   - ["wifi.sta.ssid", "s", {title: "SSID"}]
   - ["wifi.sta.pass", "s", {title: "Password", type: "password"}]
-  - ["wifi.sta.bssid", "s", {title: "Specific AP to connect to"}]
+  - ["wifi.sta.bssid", "s", {title: "Specific AP to connect to. Also used to store BSSID for quick connect (prefixed with '*')."}]
+  - ["wifi.sta.channel", "i", {title: "Specific channel to use when connecting. Also used to store channel for quick connect (as a negative value)."}]
   - ["wifi.sta.user", "s", {title: "Username for WPA-PEAP mode"}]
   - ["wifi.sta.anon_identity", "s", {title: "Anonymous identity for WPA mode"}]
   - ["wifi.sta.cert", "s", {title: "Client certificate for WPA-TTLS mode"}]

src/esp32/esp32_wifi.c

@@ -334,6 +334,7 @@ bool mgos_wifi_dev_sta_setup(const struct mgos_config_wifi_sta *cfg) {
     }
     stacfg->bssid_set = true;
   }
+  stacfg->channel = cfg->channel;
 
   if (mgos_conf_str_empty(cfg->user) /* Not using EAP */ &&
       !mgos_conf_str_empty(cfg->pass)) {

src/esp8266/esp_wifi.c

@@ -264,6 +264,7 @@ bool mgos_wifi_dev_sta_setup(const struct mgos_config_wifi_sta *cfg) {
     }
     sta_cfg.bssid_set = true;
   }
+  sta_cfg.channel = cfg->channel;
   strncpy((char *) sta_cfg.ssid, cfg->ssid, sizeof(sta_cfg.ssid));
 
   if (!mgos_conf_str_empty(cfg->ip) && !mgos_conf_str_empty(cfg->netmask)) {
@@ -473,7 +474,8 @@ bool mgos_wifi_dev_get_ip_info(int if_instance,
     struct netif *sta_if = eagle_lwip_getif(STATION_IF);
     if (sta_if != NULL) {
       struct dhcp *dhcp = sta_if->dhcp;
-      const struct mgos_config_wifi_sta *cfg = mgos_wifi_get_connected_sta_cfg();
+      const struct mgos_config_wifi_sta *cfg =
+          mgos_wifi_get_connected_sta_cfg();
       if (cfg != NULL && !mgos_conf_str_empty(cfg->nameserver)) {
         mgos_net_str_to_ip(cfg->nameserver, &ip_info->dns);
       } else if (dhcp != NULL) {