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)

TactilityCore/Source/CoreExtraDefines.h

@@ -33,3 +33,5 @@
  * @param[in] lower lower bounds for x
  */
 #define TT_CLAMP(x, upper, lower) (TT_MIN(upper, TT_MAX(x, lower)))
+
+#define TT_STRINGIFY(x) #x

TactilityCore/Source/StringUtils.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <bits/stdc++.h>
 #include <cstdio>
 #include <string>
 #include <vector>
@@ -48,4 +49,22 @@ std::vector<std::string> split(const std::string& input, const std::string& deli
  */
 std::string join(const std::vector<std::string>& input, const std::string& delimiter);
 
+/**
+ * Returns the lowercase value of a string.
+ * @param[in] the string with lower and/or uppercase characters
+ * @return a string with only lowercase characters
+ */
+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);
+}
+
+
 } // namespace

TactilityCore/Source/Timer.cpp

@@ -2,7 +2,6 @@
 
 #include <utility>
 #include "Check.h"
-#include "kernel/Kernel.h"
 #include "RtosCompat.h"
 
 namespace tt {