Add CodeQL for GitHub code scanning (#1548)

* Create codeql.yml

* Addressing codeql findings

src/hyperion-xcb/hyperion-xcb.cpp

@@ -19,13 +19,6 @@
 #endif
 #include <utils/NetUtils.h>
 
-// Constants
-namespace {
-
-	const char SERVICE_TYPE[] = "flatbuffer";
-
-} //End of constants
-
 using namespace commandline;
 
 // save the image as screenshot