GPS refactored (#262)

- Refactored GPS service and HAL: GPS is no longer part of the HAL configuration. You can now add configure new GPS devices from the GPS settings app.
- T-Deck adds a boot hook to check if a GPS configuration exists and adds it when the config is empty.
- Implemented the concept of ObjectFile to read/write arrays of a raw data type (e.g. struct) to disk.
- Implemented more file utils (e.g. to create all directories of a path)

Documentation/gps.md

@@ -0,0 +1,27 @@
+# GPS Reference
+
+## Devices
+
+### Beitian BH-222Q
+
+115200 baud, U-Blox 10 clone, defaults to binary messages
+
+https://www.beitian.com/en/pd.jsp?id=1677
+
+### Beitian BN-357ZF
+
+9600 baud, L76K clone
+
+https://www.beitian.com/en/sys-pd/879.html
+
+### GY-GPS6MV2
+
+9600 baud, U-Blox 6 (original/clone)
+
+https://www.datasheethub.com/gy-neo6mv2-flight-control-gps-module/
+
+### M5Stack GPS
+
+9600 baud, AT6558 + MAX2659 (LNA)
+
+https://docs.m5stack.com/en/unit/gps

Documentation/ideas.md

@@ -1,4 +1,5 @@
 # TODOs
+- rename kernel::systemEventAddListener() etc to subscribe/unsubscribe
 - Split up boot stages, so the last stage can be done from the splash screen
 - Start using non_null (either via MS GSL, or custom)
 - `hal/Configuration.h` defines C function types: Use C++ std::function instead

Documentation/wiring.md

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+# 4 Pin connectors
+
+Many devices have 4-pin connectors:
+Either a [Grove](https://docs.m5stack.com/en/start/interface/grove) connector or a [JST](https://en.wikipedia.org/wiki/JST_connector) one.
+
+Boards that implement an I2C/UART configuration for such a connector are advised to always implement both.
+To make it consistent, it's important that the pins are mapped in the same manner:
+
+## I2C Pins
+
+Follow the Grove layout:
+
+Black(GND) - Red(5V) - Yellow(SDA) - White(SCL)
+
+## I2C Pins
+
+Follow this Grove layout on the MCU board:
+
+Black(GND) - Red(5V) - Yellow(RX) - White(TX)
+
+And this Grove layout on the peripheral:
+
+Black(GND) - Red(5V) - Yellow(TX) - White(RX)