Code quality: Fix header guards consistency

Adds `header_guards.sh` bash script, used in CI to validate future
changes. Can be run locally to fix invalid header guards.

modules/webrtc/webrtc_data_channel.h

@@ -81,4 +81,5 @@ public:
 
 VARIANT_ENUM_CAST(WebRTCDataChannel::WriteMode);
 VARIANT_ENUM_CAST(WebRTCDataChannel::ChannelState);
+
 #endif // WEBRTC_DATA_CHANNEL_H

modules/webrtc/webrtc_multiplayer_peer.h

@@ -28,8 +28,8 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 
-#ifndef WEBRTC_MULTIPLAYER_H
-#define WEBRTC_MULTIPLAYER_H
+#ifndef WEBRTC_MULTIPLAYER_PEER_H
+#define WEBRTC_MULTIPLAYER_PEER_H
 
 #include "core/multiplayer/multiplayer_peer.h"
 #include "webrtc_peer_connection.h"
@@ -106,4 +106,4 @@ public:
 	ConnectionStatus get_connection_status() const override;
 };
 
-#endif // WEBRTC_MULTIPLAYER_H
+#endif // WEBRTC_MULTIPLAYER_PEER_H

modules/webrtc/webrtc_peer_connection.h

@@ -74,4 +74,5 @@ public:
 };
 
 VARIANT_ENUM_CAST(WebRTCPeerConnection::ConnectionState);
+
 #endif // WEBRTC_PEER_CONNECTION_H