feat(ivy): ngcc - support ngcc "migrations" (#31544)

This commit implements support for the ngcc migrations
as designed in https://hackmd.io/KhyrFV1VQHmeQsgfJq6AyQ

PR Close #31544

packages/compiler-cli/ngcc/src/migrations/migration.ts

@@ -0,0 +1,45 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import * as ts from 'typescript';
+import {MetadataReader} from '../../../src/ngtsc/metadata';
+import {PartialEvaluator} from '../../../src/ngtsc/partial_evaluator';
+import {ClassDeclaration, Decorator} from '../../../src/ngtsc/reflection';
+import {NgccReflectionHost} from '../host/ngcc_host';
+
+/**
+ * Implement this interface and add it to the `DecorationAnalyzer.migrations` collection to get ngcc
+ * to modify the analysis of the decorators in the program in order to migrate older code to work
+ * with Ivy.
+ *
+ * `Migration.apply()` is called for every class in the program being compiled by ngcc.
+ *
+ * Note that the underlying program could be in a variety of different formats, e.g. ES2015, ES5,
+ * UMD, CommonJS etc. This means that an author of a `Migration` should not attempt to navigate and
+ * manipulate the AST nodes directly. Instead, the `MigrationHost` interface, passed to the
+ * `Migration`, provides access to a `MetadataReader`, `ReflectionHost` and `PartialEvaluator`
+ * interfaces, which should be used.
+ */
+export interface Migration {
+  apply(clazz: ClassDeclaration, host: MigrationHost): ts.Diagnostic|null;
+}
+
+export interface MigrationHost {
+  /** Provides access to the decorator information associated with classes. */
+  readonly metadata: MetadataReader;
+  /** Provides access to navigate the AST in a format-agnostic manner. */
+  readonly reflectionHost: NgccReflectionHost;
+  /** Enables expressions to be statically evaluated in the context of the program. */
+  readonly evaluator: PartialEvaluator;
+  /**
+   * Associate a new synthesized decorator, which did not appear in the original source, with a
+   * given class.
+   * @param clazz the class to receive the new decorator.
+   * @param decorator the decorator to inject.
+   */
+  injectSyntheticDecorator(clazz: ClassDeclaration, decorator: Decorator): void;
+}