[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/loader/application.fam

@@ -0,0 +1,11 @@
+App(
+    appid="loader",
+    name="LoaderSrv",
+    apptype=FlipperAppType.SERVICE,
+    entry_point="loader_srv",
+    cdefines=["SRV_LOADER"],
+    requires=["gui"],
+    stack_size=2 * 1024,
+    order=90,
+    sdk_headers=["loader.h"],
+)