refactor(@angular/build): add handling for ngServerMode

Configure esbuild to add `ngServerMode` as define.

Author: alan-agius4

packages/angular/build/src/tools/esbuild/application-code-bundle.ts

@@ -507,8 +507,12 @@ export function createSsrEntryCodeBundleOptions(
 function getEsBuildServerCommonOptions(options: NormalizedApplicationBuildOptions): BuildOptions {
   const isNodePlatform = options.ssrOptions?.platform !== ExperimentalPlatform.Neutral;
 
+  const commonOptons = getEsBuildCommonOptions(options);
+  commonOptons.define ??= {};
+  commonOptons.define['ngServerMode'] = 'true';
+
   return {
-    ...getEsBuildCommonOptions(options),
+    ...commonOptons,
     platform: isNodePlatform ? 'node' : 'neutral',
     outExtension: { '.js': '.mjs' },
     // Note: `es2015` is needed for RxJS v6. If not specified, `module` would
@@ -587,6 +591,7 @@ function getEsBuildCommonOptions(options: NormalizedApplicationBuildOptions): Bu
       // which a constant true value would break.
       ...(optimizationOptions.scripts ? { 'ngDevMode': 'false' } : undefined),
       'ngJitMode': jit ? 'true' : 'false',
+      'ngServerMode': 'false',
     },
     loader: loaderExtensions,
     footer,

packages/angular_devkit/build_angular/src/tools/webpack/configs/common.ts

@@ -299,7 +299,10 @@ export async function getCommonConfig(wco: WebpackConfigOptions): Promise<Config
   if (scriptsOptimization) {
     extraMinimizers.push(
       new JavaScriptOptimizerPlugin({
-        define: buildOptions.aot ? GLOBAL_DEFS_FOR_TERSER_WITH_AOT : GLOBAL_DEFS_FOR_TERSER,
+        define: {
+          ...(buildOptions.aot ? GLOBAL_DEFS_FOR_TERSER_WITH_AOT : GLOBAL_DEFS_FOR_TERSER),
+          'ngServerMode': isPlatformServer,
+        },
         sourcemap: scriptsSourceMap,
         supportedBrowsers: buildOptions.supportedBrowsers,
         keepIdentifierNames: !allowMangle || isPlatformServer,