[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>

applications/services/gui/modules/widget_elements/widget_element.h

@@ -0,0 +1,22 @@
+/**
+ * @file widget_element_i.h
+ * GUI: internal Widget Element API
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+    GuiButtonTypeLeft,
+    GuiButtonTypeCenter,
+    GuiButtonTypeRight,
+} GuiButtonType;
+
+typedef void (*ButtonCallback)(GuiButtonType result, InputType type, void* context);
+
+#ifdef __cplusplus
+}
+#endif