Refactor app launching (#174)

- Refactor the way apps work: Instead of a C interface, they are now C++ classes. The main reasoning is that attaching data to an app was cumbersome. Having different implementations for different kinds of apps was cumbersome too. (3 or 4 layers of manifest nesting for the TactilityC project)
- External apps are still written in C, but they get a createData/destroyData in their manifest, so:
- External apps now have their own manifest.
- All functions in the original AppManifest are removed and replaced by a single `createApp` function
- External apps now automatically register (each app individually!) when they run the first time. As a side-effect they become visible in the `AppList` app!
- Adapted all apps for the new interface.
- Adapted all internal logic for these changes (Gui, ViewPort, Loader, AppContext, AppInstance, etc.)
- Rewrote parts of Loader to use std::shared_ptr to make the code much safer.
- Added a refcount check for the `AppInstance` and `App` at the end of their lifecycle. Show warning if refcount is too high.

Tactility/Source/app/ElfApp.h

@@ -1,16 +1,35 @@
 #pragma once
 
+#include "AppCompatC.h"
 #include "AppManifest.h"
 
 #ifdef ESP_PLATFORM
 
 namespace tt::app {
 
-bool startElfApp(const std::string& filePath);
+void setElfAppManifest(
+    const char* name,
+    const char* _Nullable icon,
+    CreateData _Nullable createData,
+    DestroyData _Nullable destroyData,
+    OnStart _Nullable onStart,
+    OnStop _Nullable onStop,
+    OnShow _Nullable onShow,
+    OnHide _Nullable onHide,
+    OnResult _Nullable onResult
+);
 
-void setElfAppManifest(const AppManifest& manifest);
+/**
+ * @return the app ID based on the executable's file path.
+ */
+std::string getElfAppId(const std::string& filePath);
+
+/**
+ * @return true when registration was done, false when app was already registered
+ */
+bool registerElfApp(const std::string& filePath);
+
+std::shared_ptr<App> createElfApp(const std::shared_ptr<AppManifest>& manifest);
 
 }
-
-
 #endif // ESP_PLATFORM