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/WifiSettings.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "WifiGlobals.h"
+#include <cstdint>
 
 namespace tt::service::wifi::settings {
 
@@ -13,6 +14,7 @@ namespace tt::service::wifi::settings {
 struct WifiApSettings {
     char ssid[TT_WIFI_SSID_LIMIT + 1] = { 0 };
     char password[TT_WIFI_CREDENTIALS_PASSWORD_LIMIT + 1] = { 0 };
+    int32_t channel = 0;
     bool auto_connect = true;
 };