Cleanup and improvements (#194)

- Lots of changes for migrating C code to C++
- Improved `Lockable` in several ways like adding `withLock()` (+ tests)
- Improved `Semaphore` a bit for improved readability, and also added some tests
- Upgrade Linux machine in GitHub Actions so that we can compile with a newer GCC
- Simplification of WiFi connection
- Updated funding options
- (and more)

TactilityHeadless/Source/service/wifi/Wifi.h

@@ -69,6 +69,7 @@ struct Event {
 struct ApRecord {
     std::string ssid;
     int8_t rssi;
+    int32_t channel;
     wifi_auth_mode_t auth_mode;
 };