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.defaults

@@ -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
@@ -23,8 +25,8 @@ CONFIG_PARTITION_TABLE_CUSTOM=y
 CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"
 CONFIG_PARTITION_TABLE_FILENAME="partitions.csv"
 CONFIG_ELF_LOADER_CUSTOMER_SYMBOLS=y
-CONFIG_TINYUSB_MSC_ENABLED=y
-CONFIG_TINYUSB_MSC_MOUNT_PATH="/sdcard"
+CONFIG_FATFS_LFN_HEAP=y
+CONFIG_FATFS_VOLUME_COUNT=3
 
 # Hardware defaults
 CONFIG_TT_BOARD_CUSTOM=y