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/wifimanage/State.cpp

@@ -32,15 +32,6 @@ bool State::isScanning() const {
     return result;
 }
 
-const std::vector<service::wifi::ApRecord>& State::lockApRecords() const {
-    mutex.lock();
-    return apRecords;
-}
-
-void State::unlockApRecords() const {
-    mutex.unlock();
-}
-
 void State::updateApRecords() {
     mutex.lock();
     apRecords = service::wifi::getScanResults();