esp_wifi: fix WiFi scan and connect bugs when coexist with Bluetooth

1. Fix WiFi scan leads to poor performance of Bluetooth.
    2. Improve WiFi connect success ratio when coexist with Bluetooth.
    3. Check if WiFi is still connected when CSA or beacon timeout happen.
    4. add coex pre init

components/esp32/cpu_start.c

@@ -395,6 +395,7 @@ void start_cpu0_default(void)
 
 #if CONFIG_SW_COEXIST_ENABLE
     esp_coex_adapter_register(&g_coex_adapter_funcs);
+    coex_pre_init();
 #endif
 
     bootloader_flash_update_id();

components/esp32/include/esp_coexist_internal.h

@@ -31,6 +31,14 @@ typedef enum {
 
 typedef void (* coex_func_cb_t)(uint32_t event, int sched_cnt);
 
+/**
+ * @brief Pre-Init software coexist
+ *        extern function for internal use.
+ *
+ * @return Init ok or failed.
+ */
+esp_err_t coex_pre_init(void);
+
 /**
  * @brief Init software coexist
  *        extern function for internal use.