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)

Tactility/Source/app/wificonnect/State.cpp

@@ -22,15 +22,6 @@ void State::setApSettings(const service::wifi::settings::WifiApSettings* newSett
     lock.unlock();
 }
 
-const service::wifi::settings::WifiApSettings& State::lockApSettings() {
-    lock.lock();
-    return apSettings;
-}
-
-void State::unlockApSettings() {
-    lock.unlock();
-}
-
 void State::setConnecting(bool isConnecting) {
     lock.lock();
     connecting = isConnecting;