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)

TactilityHeadless/Source/time/Time.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <string>
+
+namespace tt::time {
+
+/**
+ * Set the timezone
+ * @param[in] name human-readable name
+ * @param[in] code the technical code (from timezones.csv)
+ */
+void setTimeZone(const std::string& name, const std::string& code);
+
+/**
+ * Get the name of the timezone
+ */
+std::string getTimeZoneName();
+
+/**
+ * Get the code of the timezone (see timezones.csv)
+ */
+std::string getTimeZoneCode();
+
+/** @return true when clocks should be shown as a 24 hours one instead of 12 hours */
+bool isTimeFormat24Hour();
+
+/** Set whether clocks should be shown as a 24 hours instead of 12 hours
+ * @param[in] show24Hour
+ */
+void setTimeFormat24Hour(bool show24Hour);
+
+}