Time & date, system events and much more (#152)

## Time & Date
- Added time to statusbar widget
- Added Time & Date Settings app
- Added TimeZone app for selecting TimeZone
- Added `tt::time` namespace with timezone code

## Other changes

- Added `SystemEvent` to publish/subscribe to system wide (e.g. for init code, but also for time settings changes)
- Changed the way the statusbar widget works: now there's only 1 that gets shown/hidden, instead of 1 instance per app instance.
- Moved `lowercase()` function to new namespace: `tt::string`
- Increased T-Deck flash & PSRAM SPI frequencies to 120 MHz (from 80 MHz)
- Temporary work-around (+ TODO item) for LVGL stack size (issue with WiFi app)
- Suppress T-Deck keystroke debugging to debug level (privacy issue)
- Improved SDL dependency wiring in various `CMakeLists.txt`
- `Loader` service had some variables renamed to the newer C++ style (from previous C style)

Tactility/Source/lvgl/Init.cpp

@@ -6,6 +6,7 @@
 #include "hal/Keyboard.h"
 #include "lvgl/LvglKeypad.h"
 #include "lvgl/Lvgl.h"
+#include "kernel/SystemEvents.h"
 
 namespace tt::lvgl {
 
@@ -76,6 +77,8 @@ bool initKeyboard(hal::Display* display, hal::Keyboard* keyboard) {
 void init(const hal::Configuration& config) {
     TT_LOG_I(TAG, "Starting");
 
+    kernel::systemEventPublish(kernel::SystemEvent::BootInitLvglBegin);
+
     if (config.initLvgl != nullptr && !config.initLvgl()) {
         TT_LOG_E(TAG, "LVGL init failed");
         return;
@@ -98,6 +101,8 @@ void init(const hal::Configuration& config) {
     }
 
     TT_LOG_I(TAG, "Finished");
+
+    kernel::systemEventPublish(kernel::SystemEvent::BootInitLvglEnd);
 }
 
 } // namespace