Angular Schematics - Apply thousands of changes on tree cause error "Maximum call stack size exceeded"

# 🐞 Bug report

### Description

I use Angular Schematics to migrate from AngularJs to Angular. The application is a large one with thousands of page. I try to create a component for each page based on a template. When I try to create the component on a smaller project like 200 pages it's working but when I fall on a large one with more than 1000 pages (1000 schematics rules)

## 🔬 Minimal Reproduction

export function createPageComponents(options: any): Rule {

    return (tree: Tree, context: SchematicContext) => {

        const logger = context.logger;

        const directory = tree.getDir('my_path/pages');


        const rules: Rule[] = [];

        directory.visit((filePath) => {

            if (!filePath.endsWith('config.ts')) {

                return;

            }

            const dirPath = dirname(filePath);

            const parsedPath = parseName(dirPath, basename(filePath).split('.')[0]);

            options = {

                path: parsedPath.path,

                name: parsedPath.name

            };

            const templateSource = apply(

                url('./files'),

                [

                    applyTemplates({

                        ...strings,

                        ...options

                    }),

                    move(parsedPath.path)

                ]

            );

            const rule = mergeWith(templateSource);

            rules.push(rule);

        });

        return chain(rules);

    };

}

## 🔥 Exception or Error

    RangeError: Maximum call stack size exceeded

        at Console.warn ()

        at Observable._trySubscribe (my_path\node_modules\rxjs\internal\Observable.js:55:25)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:30:22)

        at MergeMapOperator.call (my_path\node_modules\rxjs\internal\operators\mergeMap.js:39:23)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:25:31)

        at MapOperator.call (my_path\node_modules\rxjs\internal\operators\map.js:32:23)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:25:31)

        at MapToOperator.call (my_path\node_modules\rxjs\internal\operators\mapTo.js:26:23)

        at Observable.subscribe (my_path\node_modules\rxjs\internal\Observable.js:25:31)

        at DefaultIfEmptyOperator.call (my_path\node_modules\rxjs\internal\operators\defaultIfEmpty.js:27:23)

## 🌍 Your Environment

Angular CLI: 9.1.4

Node: 10.19.0

OS: win32 x64


Angular: 9.1.4

... animations, cli, common, compiler, compiler-cli, core, forms

... language-service, platform-browser, platform-browser-dynamic

... router

Ivy Workspace: Yes

Package                            Version

------------------------------------------------------------

@angular-devkit/architect          0.901.4

@angular-devkit/build-angular      0.901.4

@angular-devkit/build-ng-packagr   0.901.4

@angular-devkit/build-optimizer    0.901.4

@angular-devkit/build-webpack      0.901.4

@angular-devkit/core               9.1.4

@angular-devkit/schematics         9.1.7

@angular-devkit/schematics-cli     0.901.7

@angular/upgrade                   9.1.9

@ngtools/webpack                   9.1.4

@schematics/angular                9.1.4 (cli-only)

@schematics/schematics             0.901.7

@schematics/update                 0.901.4

ng-packagr                         9.1.3

rxjs                               6.5.5

typescript                         3.8.3

webpack                            4.42.0

从复现代码中的 createPageComponents 入口点开始，重点查看 rules 数组和 chain(rules)，并使用超过 1,000 条 schematics 规则复现失败。结合报告中显示的 RxJS 堆栈跟踪，阅读 Angular Schematics 的执行路径。能够应用大量页面组件更改而不出现 maximum call stack 错误，即表示完成。

由索引模型根据 Issue 内容生成。