Add nlohmann json submodule third party dependency

thirdparty/json.lua

@@ -0,0 +1,23 @@
+json = {}
+
+function json:include(includes)
+	if includes:handle(self:name()) then
+		includedirs {
+			path.join(ThirdPartyFolder(), "json", "single_include")
+		}
+	end
+end
+
+function json:link()
+end
+
+function json:use()
+	
+end
+
+function json:name()
+    return "json"
+end
+
+function json:project()
+end