DRAFT: Introduce .clang-tidy

Added the .clang-tidy draft discussed here https://gitlab.eclipse.org/eclipse/simopenpass/scenario_api/-/issues/20

Applied without "llvm-header-guard" (auto fix)

DO NOT MERGE!

engine/demo/example/scenario.xosc

@@ -130,7 +130,7 @@
                       <EntityCondition>
                         <ReachPositionCondition tolerance="15.0">
                           <Position>
-                            <RelativeLanePosition entityRef="Vehicle1" dLane="-1" ds="20"/>
+                            <RelativeLanePosition entityRef="Vehicle1" dLane="-1" dsLane="20"/>
                           </Position>
                         </ReachPositionCondition>
                       </EntityCondition>