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/app/files/FileUtils.cpp

@@ -2,6 +2,7 @@
 #include "TactilityCore.h"
 #include <cstring>
 #include <bits/stdc++.h>
+#include <StringUtils.h>
 
 namespace tt::app::files {
 
@@ -69,25 +70,13 @@ bool isSupportedExecutableFile(const std::string& filename) {
 #endif
 }
 
-template <typename T>
-std::basic_string<T> lowercase(const std::basic_string<T>& input) {
-    std::basic_string<T> output = input;
-    std::transform(
-        output.begin(),
-        output.end(),
-        output.begin(),
-        [](const T character) { return static_cast<T>(std::tolower(character)); }
-    );
-    return std::move(output);
-}
-
 bool isSupportedImageFile(const std::string& filename) {
     // Currently only the PNG library is built into Tactility
-    return lowercase(filename).ends_with(".png");
+    return string::lowercase(filename).ends_with(".png");
 }
 
 bool isSupportedTextFile(const std::string& filename) {
-    std::string filename_lower = lowercase(filename);
+    std::string filename_lower = string::lowercase(filename);
     return filename_lower.ends_with(".txt") ||
            filename_lower.ends_with(".ini") ||
            filename_lower.ends_with(".json") ||