Implemented LaunchId and FileSelection, updated Notes (#281)

- Implemented `LaunchId` to keep track of the apps that are started
- Implemented `FileSelection` app to select existing and/or new files.
- Moved some re-usable file functionality to `tt::file::`
- Renamed `Files` app to `FileBrowser`
- Updated `Notes` app to use new `FileSelection` functionality, and cleaned it up a bit.
- General code cleanliness improvements

Tactility/Source/app/fileselection/FileSelection.cpp

@@ -0,0 +1,78 @@
+#include "Tactility/app/fileselection/FileSelectionPrivate.h"
+#include "Tactility/app/fileselection/View.h"
+#include "Tactility/app/fileselection/State.h"
+#include "Tactility/app/AppContext.h"
+
+#include <Tactility/Assets.h>
+#include <Tactility/service/loader/Loader.h>
+
+#include <memory>
+
+namespace tt::app::fileselection {
+
+#define TAG "fileselection_app"
+
+extern const AppManifest manifest;
+
+std::string getResultPath(const Bundle& bundle) {
+    std::string result;
+    if (bundle.optString("path", result)) {
+        return result;
+    } else {
+        return "";
+    }
+}
+
+Mode getMode(const Bundle& bundle) {
+    int32_t mode = static_cast<int32_t>(Mode::ExistingOrNew);
+    bundle.optInt32("mode", mode);
+    return static_cast<Mode>(mode);
+}
+
+void setMode(Bundle& bundle, Mode mode) {
+    auto mode_int = static_cast<int32_t>(mode);
+    bundle.putInt32("mode", mode_int);
+}
+
+class FileSelection : public App {
+    std::unique_ptr<View> view;
+    std::shared_ptr<State> state;
+
+public:
+    FileSelection() {
+        state = std::make_shared<State>();
+        view = std::make_unique<View>(state, [this](const std::string& path) {
+            auto bundle = std::make_unique<Bundle>();
+            bundle->putString("path", path);
+            setResult(Result::Ok, std::move(bundle));
+            service::loader::stopApp();
+        });
+    }
+
+    void onShow(AppContext& appContext, lv_obj_t* parent) override {
+        auto mode = getMode(*appContext.getParameters());
+        view->init(parent, mode);
+    }
+};
+
+extern const AppManifest manifest = {
+    .id = "FileSelection",
+    .name = "File Selection",
+    .icon = TT_ASSETS_APP_ICON_FILES,
+    .type = Type::Hidden,
+    .createApp = create<FileSelection>
+};
+
+LaunchId startForExistingFile() {
+    auto bundle = std::make_shared<Bundle>();
+    setMode(*bundle, Mode::Existing);
+    return service::loader::startApp(manifest.id, bundle);
+}
+
+LaunchId startForExistingOrNewFile() {
+    auto bundle = std::make_shared<Bundle>();
+    setMode(*bundle, Mode::ExistingOrNew);
+    return service::loader::startApp(manifest.id, bundle);
+}
+
+} // namespace