SD card improvements (#214)

- Implement SD card locking logic and helper functions
- Fix issue with running ELF apps from SD card: this would crash when launched from the AppList
- Reduce Boot app wait time to 1 second
- Speed up boot by about 0.1 second by moving app&service registration to the Boot app
- Files app now uses proper SD card mount point name (and multiple SD cards)
- Removed `TT_SCREENSHOT_MODE`

Boards/Simulator/Source/hal/SimulatorSdCard.h

@@ -1,6 +1,8 @@
 #pragma once
 
 #include <Tactility/hal/SdCard.h>
+#include <Tactility/Mutex.h>
+#include <memory>
 
 using namespace tt::hal;
 
@@ -9,26 +11,35 @@ class SimulatorSdCard final : public SdCard {
 private:
 
     State state;
+    std::shared_ptr<tt::Lockable> lockable;
+    std::string mountPath;
 
 public:
 
-    SimulatorSdCard() : SdCard(MountBehaviour::AtBoot), state(State::Unmounted) {}
+    SimulatorSdCard() : SdCard(MountBehaviour::AtBoot),
+        state(State::Unmounted),
+        lockable(std::make_shared<tt::Mutex>())
+    {}
 
     std::string getName() const final { return "Mock SD Card"; }
     std::string getDescription() const final { return ""; }
 
-    bool mount(const char* mountPath) override {
+    bool mount(const std::string& newMountPath) final {
         state = State::Mounted;
+        mountPath = newMountPath;
         return true;
     }
 
     bool unmount() override {
         state = State::Unmounted;
+        mountPath = "";
         return true;
     }
 
-    State getState() const override {
-        return state;
-    }
+    std::string getMountPath() const final { return mountPath; };
+
+    std::shared_ptr<tt::Lockable> getLockable() const final { return lockable; }
+
+    State getState() const override { return state; }
 };