[FL-2627] Flipper applications: SDK, build and debug system (#1387)

* Added support for running applications from SD card (FAPs - Flipper Application Packages)
* Added plugin_dist target for fbt to build FAPs
* All apps of type FlipperAppType.EXTERNAL and FlipperAppType.PLUGIN are built as FAPs by default
* Updated VSCode configuration for new fbt features - re-deploy stock configuration to use them
* Added debugging support for FAPs with fbt debug & VSCode
* Added public firmware API with automated versioning

Co-authored-by: hedger <hedger@users.noreply.github.com>
Co-authored-by: SG <who.just.the.doctor@gmail.com>
Co-authored-by: あく <alleteam@gmail.com>

firmware/targets/furi_hal_include/furi_hal_bt_serial.h

@@ -2,6 +2,10 @@
 
 #include "serial_service.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define FURI_HAL_BT_SERIAL_PACKET_SIZE_MAX SERIAL_SVC_DATA_LEN_MAX
 
 /** Serial service callback type */
@@ -38,3 +42,7 @@ void furi_hal_bt_serial_notify_buffer_is_empty();
  * @return      true on success
  */
 bool furi_hal_bt_serial_tx(uint8_t* data, uint16_t size);
+
+#ifdef __cplusplus
+}
+#endif