refactor(@angular/ssr): support building with isolatedDeclarations

This commit adds explicit return types and parameter types to the `@angular/ssr` package to satisfy the `isolatedDeclarations` compiler option.

Author: clydin

packages/angular/ssr/node/src/common-engine/common-engine.ts

@@ -65,7 +65,7 @@ export class CommonEngine {
   private readonly inlineCriticalCssProcessor = new CommonEngineInlineCriticalCssProcessor();
   private readonly pageIsSSG = new Map<string, boolean>();
 
-  constructor(private options?: CommonEngineOptions) {
+  constructor(private options?: CommonEngineOptions | undefined) {
     attachNodeGlobalErrorHandlers();
   }
 

packages/angular/ssr/src/utils/redirect.ts

@@ -9,7 +9,7 @@
 /**
  * An set of HTTP status codes that are considered valid for redirect responses.
  */
-export const VALID_REDIRECT_RESPONSE_CODES = new Set([301, 302, 303, 307, 308]);
+export const VALID_REDIRECT_RESPONSE_CODES: Set<number> = new Set([301, 302, 303, 307, 308]);
 
 /**
  * Checks if the given HTTP status code is a valid redirect response code.