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/CYD-2432S024C/Source/hal/YellowSdCard.cpp

@@ -15,7 +15,7 @@ std::shared_ptr<SdCard> createYellowSdCard() {
         GPIO_NUM_NC,
         GPIO_NUM_NC,
         SdCard::MountBehaviour::AtBoot,
-        nullptr,
+        std::make_shared<tt::Mutex>(),
         std::vector<gpio_num_t>(),
         SDCARD_SPI_HOST
     );