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

Firmware/Kconfig

@@ -17,7 +17,43 @@ menu "Tactility App"
         help
             The applications that gives access to other application.
             This is the first thing that starts after the boot screen.
-            The user can override it from a boot.properties file.
+            The user can override it with a boot.properties file
+    config TT_LVGL_FONT_SIZE_SMALL
+        int "Small font size"
+        default 10
+        range 8 200
+        help
+            Small font size in pixels
+    config TT_LVGL_FONT_SIZE_DEFAULT
+        int "Default font size"
+        default 14
+        range 8 200
+        help
+            Default font size in pixels
+    config TT_LVGL_FONT_SIZE_LARGE
+        int "Large font size"
+        default 18
+        range 8 200
+        help
+            Large font size in pixels
+    config TT_LVGL_STATUSBAR_ICON_SIZE
+        int "Statusbar icon size"
+        default 20
+        range 0 200
+        help
+            Statusbar icon size in pixels
+    config TT_LVGL_LAUNCHER_ICON_SIZE
+        int "Launcher icon size"
+        default 20
+        range 0 200
+        help
+            Launcher icon size in pixels
+    config TT_LVGL_SHARED_ICON_SIZE
+        int "Shared icon size"
+        default 16
+        range 0 200
+        help
+            Shared icon size in pixels
     config TT_AUTO_START_APP_ID
         string "Auto Start App ID"
         default ""