refactor(compiler): emit OutputAst and not sources (#16832)

This is in preparation for creating typescript nodes
directly from `OutputAst` nodes.

packages/compiler/src/aot/compiler_options.ts

@@ -14,6 +14,4 @@ export interface AotCompilerOptions {
   translations?: string;
   missingTranslation?: MissingTranslationStrategy;
   enableLegacyTemplate?: boolean;
-  /** preamble for all generated source files */
-  genFilePreamble?: string;
 }