Improvements for Files app and statusbar icon (#35)

- Created `tt_get_platform()` to use with more complex platform checks aside from the `ESP_PLATFORM` preprocessor directive
- Expand PC/sim memory to 256k so we can load the max amount of entries in Files without memory issues. I decided to skip the LVGL buffer entirely so it's easier to catch memory leaks.
- Simplified logic in `files_data.c`
- Implement statusbar as a proper widget
- Implement statusbar widget for wifi service
- Implement statusbar widget for sdcard mounting/unmounting

app-sim/src/lv_conf.h

@@ -46,10 +46,10 @@
  *=========================*/
 
 /*1: use custom malloc/free, 0: use the built-in `lv_mem_alloc()` and `lv_mem_free()`*/
-#define LV_MEM_CUSTOM 0
-#if LV_MEM_CUSTOM == 0
+#define LV_MEM_CUSTOM 1
+#if LV_MEM_CUSTOM == 1
     /*Size of the memory available for `lv_mem_alloc()` in bytes (>= 2kB)*/
-    #define LV_MEM_SIZE (128 * 1024U)          /*[bytes]*/
+    #define LV_MEM_SIZE (256 * 1024U)          /*[bytes]*/
 
     /*Set an address for the memory pool instead of allocating it as a normal array. Can be in external SRAM too.*/
     #define LV_MEM_ADR 0     /*0: unused*/