feat(@ngtools/webpack): support non-FESM angular core

APF6 does not have fESM anymore, so we need to change our logic to include
any files in core (technically there is a faster way to do this, but for now
and for testing purposes this can go it as is).

Author: hansl

packages/@ngtools/webpack/src/angular_compiler_plugin.ts

@@ -555,21 +555,15 @@ export class AngularCompilerPlugin {
     // Add lazy modules to the context module for @angular/core
     compiler.hooks.contextModuleFactory.tap('angular-compiler', (cmf: any) => {
       const angularCorePackagePath = require.resolve('@angular/core/package.json');
-      const angularCorePackageJson = require(angularCorePackagePath);
-      const angularCoreModulePath = path.resolve(path.dirname(angularCorePackagePath),
-        angularCorePackageJson['module']);
-      // Pick the last part after the last node_modules instance. We do this to let people have
-      // a linked @angular/core or cli which would not be under the same path as the project
-      // being built.
-      const angularCoreModuleDir = path.dirname(angularCoreModulePath).split(/node_modules/).pop();
-
-      // Also support the es2015 in Angular versions that have it.
-      let angularCoreEs2015Dir: string | undefined;
-      if (angularCorePackageJson['es2015']) {
-        const angularCoreEs2015Path = path.resolve(path.dirname(angularCorePackagePath),
-          angularCorePackageJson['es2015']);
-        angularCoreEs2015Dir = path.dirname(angularCoreEs2015Path).split(/node_modules/).pop();
-      }
+
+      // APFv6 does not have single FESM anymore. Instead of verifying if we're pointing to
+      // FESMs, we resolve the `@angular/core` path and verify that the path for the
+      // module starts with it.
+
+      // This may be slower but it will be compatible with both APF5, 6 and potential future
+      // versions (until the dynamic import appears outside of core I suppose).
+      // We resolve any symbolic links in order to get the real path that would be used in webpack.
+      const angularCoreDirname = fs.realpathSync(path.dirname(angularCorePackagePath));
 
       cmf.hooks.afterResolve.tapAsync('angular-compiler',
       (result: any, callback: (err?: any, request?: any) => void) => {
@@ -578,8 +572,7 @@ export class AngularCompilerPlugin {
         }
 
         // Alter only request from Angular.
-        if (!(angularCoreModuleDir && result.resource.endsWith(angularCoreModuleDir))
-          && !(angularCoreEs2015Dir && result.resource.endsWith(angularCoreEs2015Dir))) {
+        if (!result.resource.startsWith(angularCoreDirname)) {
           return callback(null, result);
         }