Filesystem improvements and more (#148)

- Rename `assets` and `config` partitions to `system` and `data`
- Change partition type from `spiffs` to `fat`, so we can have sub-directories
- Fix crash when doing WiFi scan: Increased system event task size to 3kB. 
- Free up IRAM on ESP32 (it was required for the Core2, but I also freed up the same amount for Yellow Board)
- Introduced `Paths` objects that can be retrieved by `AppContext` and `ServiceContext`. Apps and services now have their own relative paths. Assets were re-arranged into the correct paths.
- Rename simulator window title to "Tactility"
- Refactored statusbar widget so it persists icon paths properly (it kept a const char* reference, but didn't copy it, so it crashed when the related std::string was destroyed)
- Created `Partitions.h` to expose some useful variables
- Moved USB config in various `sdkconfig`  (it was part of the "default" section, but it shouldn't be)
- Updated domain name

sdkconfig.board.m5stack-core2

@@ -1,4 +1,6 @@
 # Software defaults
+# Increase stack size for WiFi (fixes crash after scan)
+CONFIG_ESP_SYSTEM_EVENT_TASK_STACK_SIZE=3072
 CONFIG_LV_FONT_MONTSERRAT_14=y
 CONFIG_LV_FONT_MONTSERRAT_18=y
 CONFIG_LV_USE_USER_DATA=y
@@ -24,6 +26,7 @@ CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"
 CONFIG_PARTITION_TABLE_FILENAME="partitions.csv"
 CONFIG_ELF_LOADER_CUSTOMER_SYMBOLS=y
 CONFIG_FATFS_LFN_HEAP=y
+CONFIG_FATFS_VOLUME_COUNT=3
 
 # Hardware: Main
 CONFIG_TT_BOARD_M5STACK_CORE2=y
@@ -32,7 +35,6 @@ CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_240=y
 CONFIG_ESP32_DEFAULT_CPU_FREQ_240=y
 CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
 CONFIG_FLASHMODE_QIO=y
-CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH=y
 # Hardware: SPI RAM
 CONFIG_SPIRAM=y
 CONFIG_SPIRAM_MODE_OCT=y
@@ -42,3 +44,8 @@ CONFIG_SPIRAM_TRY_ALLOCATE_WIFI_LWIP=y
 CONFIG_LV_DISP_DEF_REFR_PERIOD=17
 CONFIG_LV_INDEV_DEF_READ_PERIOD=17
 CONFIG_LV_DPI_DEF=139
+# Fix for IRAM
+CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH=y
+CONFIG_FREERTOS_PLACE_SNAPSHOT_FUNS_INTO_FLASH=y
+CONFIG_HEAP_PLACE_FUNCTION_INTO_FLASH=y
+CONFIG_RINGBUF_PLACE_FUNCTIONS_INTO_FLASH=y