Add HTTP & SOCKS5 proxy support (#4321)

This can be configured using the `CHATTERINO2_PROXY_URL` environment variable.
The behaviour is similar to curl's CURLOPT_PROXY

src/main.cpp

@@ -1,9 +1,11 @@
 #include "BrowserExtension.hpp"
 #include "common/Args.hpp"
+#include "common/Env.hpp"
 #include "common/Modes.hpp"
 #include "common/QLogging.hpp"
 #include "common/Version.hpp"
 #include "providers/IvrApi.hpp"
+#include "providers/NetworkConfigurationProvider.hpp"
 #include "providers/twitch/api/Helix.hpp"
 #include "RunGui.hpp"
 #include "singletons/Paths.hpp"
@@ -81,6 +83,8 @@ int main(int argc, char **argv)
             attachToConsole();
         }
 
+        NetworkConfigurationProvider::applyFromEnv(Env::get());
+
         IvrApi::initialize();
         Helix::initialize();