component/bt: legacy bt API provide

1. move btif module out of bluetooth stack
2. provide new APIs in bluedroid/stack_api

components/bt/bluedroid/stack_api/bt_gap_api.c

@@ -0,0 +1,35 @@
+#include "bt_gap_api.h"
+#include "bta_api.h"
+#include "bt_trace.h"
+
+esp_err_t esp_bt_gap_set_scan_mode(bt_scan_mode_t mode)
+{
+    tBTA_DM_DISC disc_mode;
+    tBTA_DM_CONN conn_mode;
+
+    switch(mode) {
+    case BT_SCAN_MODE_NONE:
+        disc_mode = BTA_DM_NON_DISC;
+        conn_mode = BTA_DM_NON_CONN;
+        break;
+
+    case BT_SCAN_MODE_CONNECTABLE:
+        disc_mode = BTA_DM_NON_DISC;
+        conn_mode = BTA_DM_CONN;
+        break;
+
+    case BT_SCAN_MODE_CONNECTABLE_DISCOVERABLE:
+        disc_mode = BTA_DM_GENERAL_DISC;
+        conn_mode = BTA_DM_CONN;
+        break;
+
+    default:
+        // BTIF_TRACE_ERROR("invalid scan mode (0x%x)", mode);
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    // BTIF_TRACE_EVENT("set property scan mode : %x", mode);
+    BTA_DmSetVisibility(disc_mode, conn_mode, BTA_DM_IGNORE, BTA_DM_IGNORE);
+    
+    return ESP_OK;
+}