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

Data/data/test.txt

@@ -0,0 +1,2 @@
+This file exists to test the partition.
+It can be deleted when the partition contains other files.

Data/system_sources/app/Desktop/apps.svg

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Data/system_sources/app/Desktop/folder.svg

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+<svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 -960 960 960" width="24px" fill="#e8eaed"><path d="M160-160q-33 0-56.5-23.5T80-240v-480q0-33 23.5-56.5T160-800h240l80 80h320q33 0 56.5 23.5T880-640v400q0 33-23.5 56.5T800-160H160Zm0-80h640v-400H447l-80-80H160v480Zm0 0v-480 480Z"/></svg>

Data/system_sources/app/Desktop/settings.svg

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