[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/debug/accessor/accessor.cpp

@@ -0,0 +1,11 @@
+#include "accessor_app.h"
+
+// app enter function
+extern "C" int32_t accessor_app(void* p) {
+    UNUSED(p);
+    AccessorApp* app = new AccessorApp();
+    app->run();
+    delete app;
+
+    return 255;
+}