Implement UI scaling and more (#501)

**New Features**
 * Runtime font accessors and new symbol fonts for text, launcher, statusbar, and shared icons.
 * Added font height base setting to device.properties
 * Text fonts now have 3 sizes: small, default, large

**Improvements**
 * Renamed `UiScale` to `UiDensity`
 * Statusbar, toolbar and many UI components now compute heights and spacing from fonts/density.
 * SSD1306 initialization sequence refined for more stable startup.
 * Multiple image assets replaced by symbol-font rendering.
 * Many layout improvements related to density, font scaling and icon scaling
 * Updated folder name capitalization for newer style

Platforms/platform-posix/source/freertos.c

@@ -0,0 +1,20 @@
+#include <stdlib.h>
+#if defined(__GLIBC__)
+#include <assert.h>
+#endif
+#include <tactility/freertos/task.h>
+#include <tactility/log.h>
+
+#define TAG "freertos"
+
+/**
+ * Assert implementation as defined in the FreeRTOSConfig.h
+ */
+void vAssertCalled(unsigned long line, const char* const file) {
+    LOG_E("Assert triggered at {}:{}", file, line);
+#if defined(__GLIBC__)
+    __assert_fail("assert failed", file, line, "");
+#else
+    abort();
+#endif
+}