[IMP] qweb: slightly simplify generated templates

- In some cases, we can simply inline a template key instead of assigning
  it to a variable and then using that variable
- Add component name in generated code for components

src/component/directive.ts

@@ -189,7 +189,7 @@ QWeb.addDirective({
   extraNames: ["props"],
   priority: 100,
   atNodeEncounter({ ctx, value, node, qweb }): boolean {
-    ctx.addLine("//COMPONENT");
+    ctx.addLine(`// Component '${value}'`);
     ctx.rootContext.shouldDefineQWeb = true;
     ctx.rootContext.shouldDefineParent = true;
     ctx.rootContext.shouldDefineUtils = true;